Self hosting a Lemmy instance for just myself?

Heya, I'm trying out Lemmy and kinda like the idea of hosting a Lemmy instance just for me.

I was wondering:

• What are the hardware/bandwidth requirements for a single user instance?
• I know different instances can black list each other, but can they whitelist each other too? I don't want to be automatically unable to see interact with certain instances.
• Has anyone else done this and have thoughts to share?
• What about doing the same for Mastodon?