Just don't try to run huge amounts of bandwidth or try to pirate content on it and you'll be fine.
It does need a credit card on file, but it cannot charge it unless you explicity disable free tier.

Tried a few weeks ago. They wanted my card to check that I am not a bot (I am fine with that), the 0usd transaction succeeded but then I got an error message.

God knows what they'd have flagged. I was trying to sign up to sendgrid's free tier to test their SMTP server and got instabanned before I even got the verification email.

My main use currently is a modded Minecraft server. But I want a VPS over one of those Minecraft host specifically because I plan on messing around with docker containers later and hosting my own Lemmy instance. Currently I have a openVZ server from TNA hosting because it was like $50 a year. But it's not powerful enough for the Minecraft modpack.

So what VPS provider would you lot recommend?

Second racknard. If you Google Black Friday special, you'll find the page where you can order a VPS with four gigs of RAM for something like $50 a year. It's not a 12-month special either, you can renew it year after year.

I run docker containers there, a Red Dead redemption 2 server, etc. It's really useful commodity server to have around,

My main use currently is a modded Minecraft server. But I want a VPS over one of those Minecraft host specifically because I plan on messing around with docker containers later and hosting my own Lemmy instance. Currently I have a openVZ server from TNA hosting because it was like $50 a year. But it's not powerful enough for the Minecraft modpack.

So what VPS provider would you lot recommend?

@secret300 Ethernetservers.com

3rd racknerd -- but I just use the cheapest KVM deal in the geographic region I need it in. About $10/yr for single core older Xeons with 768M-1G RAM. Still though I've been very happy with them.

Is that enough resource to use as a VPN?

You can get a quad core ARM 24 gb ram vpn for free on oracle cloud on their free tier.