I haven't implemented the Mastodon API in my own work because it's ultimately based on Twitter (we implemented the Twitter/StatusNet API back in 2010 and still provide it - even though there are very few clients remaining).
The problem is that the Mastodon API (and the Twitter/StatusNet API) don't support more than about 25% of our software functionality; which is closer to Facebook (although with a decade and a half of enhancements) than Twitter/X. We also support the ActivityPub API -- but alas there aren't any viable clients. And don't tell me about AndStatus. That's supports the ActivityPub API but which can only be used with undocumented features of Pleroma's implementation of the Mastodon API. So we're back to the Mastodon API and Twitter. Nope. And nope.
We use Progressive Web Apps anyway. The two app stores controlled by corporate oligarchs have to die.