BitcoinHackers adds new users only infrequently.

You might find https://mstdn.social to be an instance that is fairly good. In addition to being on BitcoinHackers, I'ld been on two other instances prior (one dropped me for "COVID misinformation", and the other shut down suddenly), so I was happy that mstdn.social has been there. Another instance, https://c4.social, is run by a bitcoiner but I have no idea if it is open publicly. I suspect it is.

It really matters less what instance you are on once you have followed a number of users then your Home timeline is more useful than the Local timeline.

If you wanted to fast-track a list of bitcoin-related users to follow, I have a list you can import:

Mastodon-Who-To-Follow https://github.com/cointastical/Mastodon-Who-To-Follow#mastodon-who-to-follow