but not individual instances.

You can. If you're using a Lemmy home instance, as you are currently (lemmy.world), in the Web UI, go to your user menu in the upper-right corner, click "Settings", click the "Blocks" tab, and then you can choose instances to block in a panel there.

If what you want is "I don't want auth-left stuff", avoiding hexbear.net, lemmygrad.ml, and lemmy.ml can help. You aren't going to get some kind of ironclad avoidance, but that'll avoid the great bulk of it. Your home instance is lemmy.world. lemmy.world is defederated with lemmygrad.ml and hexbear.net for exactly the reason you mention (in fact, I see people who don't like lemmy.world because they consider it liberal, which they don't like) so you already won't be seeing stuff from the first two instances.

I don't think I've personally seen fascist material on the Threadiverse (though there are some people with quite broad definitions of the term), though there are or were some far-right instances out there, based on defederation lists. Most of what little I've seen on the Fediverse seems to me to be on Pleroma, though I haven't spent much time on non-Threadiverse Fediverse stuff.

moderate conservative

The home instance that I use, lemmy.today, has one user (@DonaldJMusk@lemmy.today) that posts a bunch of Trump stuff and a conservative community, !conservative@lemmy.today. I don't know if your definition of conservative and his match up, but maybe you'd find it to your taste; it's probably the closest to mainstream US, Republican material that I've seen with much activity on the Threadiverse. The instance isn't going to be just moderate conservative and moderate liberal users though. But, if that's the kind of community that you might be participating in, I'd imagine that he'd like to have more users.

EDIT: My own personal take is that the long term solution to having people with disparate positions on what content they want to see, above-and-beyond use of moderated communities and admin activity on instances, is to have "curator lists", where people can basically "share" lists of blocks/subscribes/votes or something like that, and other users can subscribe to them. Then you have a list that

for example

excludes or includes content on various grounds without requiring effort on a per-user-who-wants-curated-content basis. I think that Usenet pretty much established that killfiles don't really scale well in combating spam and stuff like that, because there was never a mechanism to share killfiles among users. Anyway, today, there isn't support for something like that on the Threadiverse. I understand that BlueSky has something along those lines.

You can block individual instances, I have a long list of instances that I have blocked.

You're not alone in this. Just keep blocking the offending communities or instances until your feed's balance suits you.

I use piefed.social because it 's easy to filter out what I consider noise (aka most political content and all kind of excited people ;)

Maybe have a look again, as I at least could block instances if I wanted to.

I am happy with only having blocked some communities, though.
Mainly the too US-centric political ones.

Interestingly enough that also got me rid of a large part of the more ridicously exaggerated tankie stuff I encountered before.

Are different communities/servers really all that similar? I kinda just assume that people choose a somewhat random instance when they start and stick with it.

goes on communist website
built by communists that got kicked out of reddit
i like this, but what about all those communists???

I largely use Lemmy because it doesn't tolerate conservatives.

It's 2026. There is no such thing as a moderate conservative. They don't deserve the benefit of the doubt. They don't deserve yet another platform to argue in bad faith on. They've gone too far. Every platform they touch turns into a cesspool of bigotry and garbage opinions they think should be taken seriously or they play victim.

I don't want them on Lemmy.

Real life. If you want moderate, complex opinions. Talk to real people. Not the bots and shills that populate this place.

You want an online community that allows both the right and the far right? That would be ALL OTHER ONLINE COMMUNITIES!

We came here specifically to get our own forum, where the centre left, regular left and far left are all allowed. This is a forum for the working class, not for the capitalists. And you capitalists can't handle the fact that us workers for once get to have a forum of our own.

Piefed makes it much easier to block instances.

As someone said, you can block instances but it can be useful to look up an instance on fediseer. It shows endorsements and censures for the instance along with other information:

https://gui.fediseer.com/instances/detail/lemmy.world

None. Because that would mean that humans on Earth are being reasonable.

Have you met people? People are the worst.

Reasonable Moderate Conservatives don't exist, idiot

I've heard of something called Facebook that's supposed to be quite conservative. But, I've never visited it.

From what I can tell, Lemmy started as wildly left but if you avoid the .ml areas, you're going to get a much broader mix of views.

If someone planned to divide and conquer lemmy, they did a fine job. You can tell lemmy is left leaning by how fractured everything is. And it's mostly filled with leftist who hate anyone left from where they are.

Reddit also died. It's now a museum piece of dead internet theoy.

I find that the trick - or at least the idea - isn't to go out of the way to avoid such political discussions; it is to seek out spaces with some niche interest. Discussions would then naturally gravitate around the topic of interest, and political discussion usually doesn't make sense in such a space.

An example topic is anime. Most anime are not political in nature, so commenters in ani.social don't have the chance to go off-topic and discuss politics.

To use an analogy, let's say you are a picky eater. You are given some food (think soup, salad, etc), but one of its ingredients is something you don't like. Rather than try to pick out that one ingredient you dislike bit by bit (which can be tedious), how about adding condiments / dressing / etc to the dish? Enough of those and the taste would change, with the newly-added tastes having overpowered the one you dislike.

In terms of implementation, you basically have to curate your feed somehow. On Lemmy, the straightforward way to do so is to subscribe to topics / communities you are interested in, and participate in just those.