I keep my dropouts free ebooks in Dropbox and use moonreader + to read them and sync across devices. Until I lost my library in a hdd failure I had 10k books self hosted with calibre and that was straight forward and worked well. I do also use Google Books for things I buy and like it although it lacks some QoL features of moonreader
I used it on a relatives computer recently. On streaming sports sites it got about 90% of ads but did miss the transparent overlays that open a new page when clicked. UbO handles all of that just fine.