I could see a lot of Fedimint providers acting like credit unions for a local area, university, industry, etc.

Loans done the correct way could be a source of income. Users can anonymously lock up a portion of their funds to earn interest. The Fedimint provider then loans out whatever is available from the pool of locked up funds. The Fedimint provider can do proof of reserves to ensure its users that they aren't rehypothecating their funds or engaging in fractional reserve banking. Like with most loans, now the users have to trust the borrower to pay the provider back. So these borrower would be subject to a lot of scrutiny.

Fedimint providers could charge a fee to businesses and make it free for individuals. Storing large amounts of bitcoin and/or providing inheritance services could also be subject to a fee or subscription.