It boils down to two broad categories for me:
- How locked down the OS is on iPhones and iPads. We’ve seen recent progress (Safari extensions, retro console emulators), but we’re still far from a serious OS. iOS still lacks a proper file management system (especially for playing back local audio) and no side-loading is still a deal breaker.
- Obscene markups for easily accessible parts. Apple still believes 8GB RAM is worth $200, and they believe 1TB storage is worth $800. I’d rather just get something with replaceable RAM and storage.
I use Calc84 on the Google Play store, free with minimal ads and a one-time fee to remove ads.
But it seems like others have found FOSS versions here.