Not sure if you are trolling, but no
Meta is joining the Fediverse not because it needs the people currently on the Fediverse, but because it needs a regulatory figleaf to protect itself from monopoly charges. At Meta’s scale, there are 0 users on the Fediverse right now. There is no market benefit to getting Fediverse people to move to Meta
What Meta gets out Threads/Fediverse compat is that suddenly Instagram is not technically a walled garden with platform lock-in, so while the number of people who’ll migrate from Instagram Threads to the Fediverse is going to be tiny they suddenly look a lot less like a mean monopoly to regulators
At some point they might remove the Fediverse compat. The people currently screaming about embrace-extend-and-extinguish because Meta is joining will then scream about bait-and-switch even though they’ve had Threads defederated the whole time. The Fediverse will still be there. That’s the cycle of life
Moves like this always assume that location equals citizenship. As an EU citizen living in North America, a move like this means that I would not get the remedy that Apple legally owes me (or would owe me if I owned an iOS device)
The main thing I’ve been sideloading on Android for a decade is a fan implementation of the Dominion card game called Androminion. It was trademark cease and desist removed from the Play Store a decade ago, but you can still get the apk on Github
There’s a couple other things. One big gap in both the Google and Apple stores is the complete absence of adult content. I’m amazed there’s not more of a clamour for adult apps among either userbase, given that most people don’t own a normal computer. Sideloading could plug that gap