No, I dont. The machine is wayyyy overspecced for these services, 6 cores, 16 GB of ram. What isnt overspecced is is the drive, 100 GB of nvme are fast but not enough for all my projects. I have taken a lot of measures to confine the services but mastodon is pretty much the worst offender afaik. Lemmy is the most intensive ram and cpu hog it has strong spikes every hour. You dont need six cores, two would most likely suffice. I think its a ryzen 5600 but not sure atm.
Average users are one each. A couple of friends have accounts but they dont usually use them. Federations is no big issue, single user instances could definitely be done from home, large instances should def be faster than my upload at least. Moving later is a pain so I‘d plan accordingly.
Maintenance is very hard if you do it manually, which I dont. Automate backups off site so a hack cant get the backups. Dockerize to hell and back, have fail2ban. Updates will break sometimes so make yourself familiar with docker and linux if you arent, otherwise you’re screwed as are your users. I‘d probably start with a solo server, then invite friends (beta testers) and then open to the public. You will also be defederated if you just open up to the public. Legal issues notwithstanding.
I hope this makes sense. Feel free to ask follow up question.
Should be fine as long as they have different domain names and your virtual hosts are setup to route to the correct services.
I've got Lemmy and Matrix sharing the same app and database servers without issues; just make sure the servers are sized and tuned to handle both applications' loads.
In a way. I have a WordPress blog with an ActivityPub plugin to also publish to Mastodon. It's on a different domain than my Lemmy instance.
Only thing I had to do was to set up Apache as a proxy for the Lemmy Docker. Apache can serve different stuff depending on the domain. Nginx can probably do that as well.