I keep thinking of trying Mastodon but then stop because I just don’t think I’ll find enough or be able to interact enough. Having a tool and someone to follow initially should help!

This thread from a few days ago: "Ask HN: Who are your favourite people to follow on Mastodon?"

https://news.ycombinator.com/item?id=16741116

You could always have a look here, it's a tool to find out which of your Twitter friends already are on Mastodon: https://bridge.joinmastodon.org/

If you join an instance that caters to an interest of yours, then you can look at the "local timeline" which shows only public posts on your instance.

There's also this instance:

https://mastodon.technology/about