>>281410278
You know what, you could actually do this though

There are guides for grammar in romaji, so that step's easy
You could convert an initial frequency list anki set for the most common words into pure romaji and start with that too
Then you'd need some sort of into-romaji translator for japanese subtitles, this shouldn't be that hard to do considering what jpdb can already do with mpv - and some sort of interactive word lookup in romaji subtitles - also should be doable, modify what people currently do with yomitan and mpv to only display romaji and that's it