Using Amazon Fire HD8 Plus, 2.7 GB RAM, Android 9

I use both Opera [65.2.3381] and Opera beta [66.0.3425], my favorite browsers for my common use. I am online throughout day, via browser, visiting many sites for research, bookmarking and closing most tabs while other tabs remain active.

Over time many tabs remain open, despite closing many more, then consequently, over long time, either browser no longer opens, or rather do not fully launch before crashing. Typically, I reboot, go through cache cleaners and task managers to close as many things as possible and maximise available RAM. Usually this helps in getting one or the other to load while disconnected from Internet and I close as many tabs as I can afford.

Now even this doesn't work, neither browser loads, no matter what I do. I cannot afford to lose my myriad bookmarks. Someone recommended using ES File manager to backup into a unique apk, though there was no insight as to whether that would backup data ... the apk made was 80.* MB.

Your seasoned practical wisdom welcomed.