[AnotherCat]

I have Moon+ Reader Pro and PocketBook apps (PocketBook is free), both of which I prefer over others and both of which I use on phone and tablet. Perhaps they are "bloated and resource-hungry" but I have noticed no symptoms of such when using them so had no need to worry whether they were so or not. For myself, out of those two, I prefer and use PocketBook most despite its unconventional menu structure.

Both work fine on my phone which is Android 9 Pie - phone is in the Android One program so is stock Android 9.

I have not checked for a while, so take this with a grain of salt and accepting that I know the low level of relevance of PDFs to small devices, but I had found that PocketBook handled PDFs better than Moon+ Reader Pro. However, in the unlikely event it is useful I use Xodo for PDFs on phone and tablet.