Use the net installer. Leave the root password empty if you want sudo installed. There is probably no need for you to read the official installation manual, but maybe do so if you run into any trouble.

There are wiki pages for the most common things you might want to setup, like how to install steam, nvidia driver, enable backports (good way to get (some) newer packages without breakage), and enable flatpak. Just google "debian wiki nvidia" etc.

Maybe a bit naive, but what is the way that things that are going? What would Canonical pulling the rug out look like?

If you're already into self hosting, programming, networking and automation then I don't think you'll have any trouble.
With that background you should be able to google the solutions.

Debian offers you 3 variants of Debian:

Debian stable (what you get by default from their homepage). https://wiki.debian.org/DebianStable
Debian testing (has newer packages than stable and breaks less often than Debian unstable). https://wiki.debian.org/DebianTesting
Debian unstable (has the most recent packages and is considered the most fragile of all). https://wiki.debian.org/DebianUnstable

Use configuration as code. Ansible, puppet, salt, nix or something else. Debian is nice but its a diy ubuntu. You appreciate the effort cononical puts in to take away the rough edges on places. Using debian allows you to craft the OS you want from scratch, which is great! Just make sure you don't have to redo work if your system dies at some point.

You may want to try pop_os if one of your main uses is gaming. But debian is very straight forward after you enable the non-free repos.

Switch to Fedora I would say. Debian is up to date currently, as things are settling down to be LTS, but over the years it will get fewer updates. Fedora is even more up to date than Ubuntu, but more stable than Opensuse Tumbleweed, which would be the Opensuse equivalent.

If you want a perfect experience with KDE, I dont know what to recommend but there are bugs that will probably simply not be fixed in Debian for the next 2 years, as they are postponed to Plasma 6, mainly the glitches when fractional scaling.

Gnome is really stable I think, Fedora should give the best experience here.

Btw using Distrobox you can run ANY Linux app easily. On Fedora Kinoite (ostree, like Silverblue) I run the VLC 4.0 beta currently, which is only available as an Ubuntu PPA. no problem at all. Do mainly for AUR or Ubuntu PPA apps Distrobox is brilliant.

Fedora itself also has COPR where lots of community packages are.

If you want recent deb-based, there also is KDE Neon user edition. Used that for a while, but I switched to immutable Fedora and never going back.

Just Mint it dude

I just switched from Linux Mint to Linux Mint Debian Edition (LMDE). I was feeling like you; wanting to get away from Ubuntu dependency. I tried out Debian, but it just didn't feel as comfy out of the box. LMDE is working great. I even enabled backports and updated the Kernel.

No tips needed; everything will work rock-solid and you'll never return to Ubuntu

Just learn how to activate the non-free repos. Everything else except for the stupid stuff like snap that ubuntu introduced, is 99.5% the same. I've switched from Ubuntu to Debian like 15 years ago. Never looked back.

If you install Steam/Lutris/Bottles as a Flatpak it will use an updated Mesa stack when you run games through them. If you need a newer Linux kernel you can use the official backported version or something like Xanmod's MAIN branch/Liquorix.

That's pretty much it, and you may not even need those changes depending on your hardware. I recently wrote a comment on how I use Debian Stable if you want some extra opinions on how to make Debian Stable a little more livable.

I’ve heard gaming on debian isnt as ‘out of the box’ as it is with Ubuntu.

Depends on what your hardware is. Debian typically runs some older versions of pretty much everything. If you have newish hardware, you might need to run a newer kernel than Debian ships by default for full support. When that happens to me, I usually run the Liquorix kernel packages, which has been around for more than a decade and has never caused me problems on Debian.

For some graphics drivers, you might need a newer Mesa, which is typically available from Debians' own backports.

Don't do either unless you know you need to, because both lead to a somewhat higher risk for an unstable system.

You can just install Steam using Flatpak, and it works just fine.

On server I found it to be basically the same except for some installed programs. Dunno about gaming doe.

Why not try Mint? Also Debian based

Install your base system and get every app you need using flatpak. That way you'll get the latest versions without poluting your system. It even integrated with the GNOME Software "store" GUI: https://flatpak.org/setup/Debian

No idea if Ubuntu does some things better for gaming, but I just use the Steam Flatpak (+ the "steam-devices" package for much better controller support) and the Heroic Game Launcher Flatpak. Everything works fine on my end. I'm currently using an AMD card, but will probably switch to an Intel Arc in the near future (since they have better performance for 3d rendering in Blender, and I'm fed up with Nvidia's prices).

Tangential question for people browsing this post: would you recommend a different Linux distribution over Debian and Ubuntu for OP? If so, which one and why?

I doubt you would need any tips, also right now Bookworm is closer to upstream than Ubuntu, so it's better fit for gaming sans some niche missing package scenarios that won't matter if you heavily rely on flatpaks.

The only major thing Ubuntu has over Debian is the normie friendly graphical , but it's not great so /shrug .

Also Canonical is not going to pull the plug, that's one thing you don't really have to worry about, unless they sell the company.