I've only heard of asbplayer and Anki miner before, the others I haven't. It's a great space tbh, people are building all the time. For me specifically it's about trying to serve all languages to the best of my ability, alot of the ones I've come across only focus on Japanese or a small selection of languages. Also I think there's scope to improve UX and reducing friction for non tech savvy people

even for "tech savvy" people, it's great to have an easier to use UX, or at least have the option to

Migaku is far from perfect, but it's fairly polished and supports a ton of languages. Honestly, I wish it just focused on a couple of languages and did them well instead of trying to support as many as possible, though.

In my experience, apps for learning japanese is a hugely saturated niche because the venn diagram of people learning japanese and people who like building software is a circle

Yeah, all in one apps are now getting built every other week

I think it would be interesting to try this with another language though. Picking something like Russian or something obscure like Turkish could be a more undeserved segment