There are signing keys involved, so if someone puts up a new server but uses different keys then all sorts of federation trouble will await them.
That said it shouldn't affect the general network, just that individual server (both the communities and the users of it)
Edit: As for switching domains on an existing server, that would be equally troublesome as ActivityPub kinda relies on domains for all sorts of IDs.
It's possible by having the webfinger endpoints at the "root" while keeping the rest of Lemmy on a subdomain. The main thing that determines the domain in your username is webfinger.
No clue if Lemmy or kbin support this config though, but quite a bit of the microblog-only parts of fedi do, and it's a widely used thing.
jsyk, with how ActivityPub works changing the software that's running from under it will break federation with you in all sorts of subtle ways. When you pick a thing to run under a domain you're effectively locked into running that software under that domain. And of course there is some cryptographic verification as well so you change the keys (or you wipe or forget to back up the database) you may as well burn that domain from federating ever again.
On a desktop or especially laptop case, it should be equal to (or larger than) your RAM if you use hibernation (as RAM gets copied to swap during hibernation)
On my server, I set it up to be 2GBs, mostly arbitrarily. Right now it's at 500MB, but my main memory is also only 600-800MB full out of the total 4GBs available, so I'm not running out of RAM anytime soon.
Swap behavior seems to have changed a while ago, so consider reading https://chrisdown.name/2018/01/02/in-defence-of-swap.html on how it works right now. Hell, even that might be outdated nowadays. Up to date info on how swap works really seems hard to come by.
Moreover I also have my swappiness set to 0 because I don’t want stuff swapped out of memory. If I need more memory I need more memory.
I don't think swappiness has worked that way for a while now.
People aren't against companies, people are against Meta. In the wider fediverse, anyway.
A while back there was talk of Tumblr potentially joining the fediverse, and it was met with neutral to positive reactions. No idea what happened there, maybe they're still working on it, but I do not expect a "fedipact against tumblr" to gain as much steam (if any) when they decide to announce they're ready to flip the ActivityPub switch.
(no idea if my other comment got sent out, this may be a duplicate)
Tildes was always invite only. Granted it is (or was at the time, maybe they slowed down with the influx) really easy to get your hands on one by just asking on r/tildes (or email).
Hell, the site being readable by the general public is a relatively recent introduction compared to it's history.
Your private messages are never private unless you're on a platform that specializes in private messages (Signal. Matrix, WhatsApp (if they are to be believed), XMPP via OMEMO...)
Flatpak will sandbox most app data under $HOME/.var/app/. Of course it doesn't tell you this because you're supposed to already know this, stupid. (issue locked) (works as intended), but that's where you should dig if you need that old save (or want the security of Flatpak while playing Minecraft).
I wonder if there are any file browsers that special case that directory and show an "app data" view. That sounds like a feature request someone must've opened by now.
Tumblr - both as the userbase and as the company - has been pretty "cool" compared to Facebook/Instagram (which isn't a high bar, really). I think most people are indifferent to favorable on letting them in here if they decide on doing that.
I think they're "getting their feet wet" with federation with an official WordPress plugin (Tumblr is now owned by the company that develops WordPress) first, before deploying it on Tumblr.
I wonder how well it integrates with hardware. Arch with the pacman packages has been the only distro where I could get ROCm working reliably. I'd love to make a "ROCm container" and dump all that mess into it's own sandbox.
In fact, the thing I really want is more of a "Qubes but not for security tryhards" (aka I can actually use Wayland AND game on it) where everything gets it's own container mainly for organizational purposes, but something like this sounds like a fair compromise.