I used messagease keyboard before (the only non-foss app on my phone). So I am happy to have a foss keyboard now. I'm still with the normal messagease layout and nowhere near 50 wpm. I like to have full control over what I write, including brackets and other symbols, mostly for markdown. I usually type with one hand and am about as fast on left vs. right. I also like having a 3x3 numeric keyboard. I'm not sure if this can be configured on thumb, but I coud type single digits by long pressing a button on messagease.
I never liked predictive typing, maybe because i did too many errors on my small screen (<5").
It is ok to fall asleep in 30-100h gaming sessions. I'm sure you can do a 90-120 minute movie.