You can, but I'll caution you against doing so if at all possible. Try to find an existing smaller space to post within. Lemmy is not reddit in size. There is a very different potential for ultra niche communities here. Giving up on reddit is hard in that you likely have an emotional addiction on some abstract level. This is just like a breakup in that adjustment takes time. If you try to shape a new partner into the form of your last, things tend to end badly.

Most new niche communities here are more like blogs. It is a major uphill battle to create something that is self sustained and has others posting regularly. Unless you are very skilled at driving popularity, you will likely struggle.

However, you will likely find acceptance in a more general space. It is far better to start in a more general space and if you find the comradery, or your regular collective dominance with others becomes an issue, then branch from that base and start a new community.

I'm a nobody and no authority here. You do you. This is just what I have observed as successful versus the many that are not in the last 2 years.

Since your account is on Feddit.nl, you just go here and create the communities: https://feddit.nl/login?prev=%2Fcreate_community

Then you can introduce them in this community:

!newcommunities@lemmy.world