Technically this can be implemented in Anki as an addon. But only the desktop version supports addons and the default UI is a bit too complicated.
Impressively, Mochi now offers FSRS (beta but still available in the app's main settings) and both the type of scheduler (Mochi default or FSRS) and the schedulers' settings are configurable on a deck-by-deck basis.
The developer is very responsive to folks on the forum and often quickly adds requested features.
Overall the app is well-designed and fun to use. I appreciate the swipe left/right to fail/pass cards on iOS. My one complaint is that the web clipper only works with Chrome and Firefox, but not with Safari (surprisingly). It would also be useful to have a global hotkey/palette to quick-add cards to various decks, similar to how OmniFocus lets you quickly add items to the OF Inbox.