Yes, I am using mlem. The only problem I had was an issue with setting up testflight — I had to copy and paste the code from the URL that mlem gives you

My understanding is that one implication of the API cost is that it will impact the cost of running bots/automation of moderation tasks. If this is true, I don’t think it matters much that they are allowing some third party apps if all the subs get overwhelmed with spam and bots.