As per an official statement from Asus - it is not true that their Zenfone series is going to end with 10.
https://press.asus.com/news/asus-zenfone-10-to-continue-production/
I use MiXPlorer.
It’s free (not sure if FOSS), and there are non-essential-but-nice-to-have features that are paid, just to support the dev - but the free features are awesome, and more than enough for me.
The only paid app that I have is Moon+ Reader Pro.
I read a boatload of ebooks on my device, and this has been my ebook-reader of choice for a while. I found it to be so good that I did the IAP, and stopped using Librera Reader.
For all that matters, I am a huge supporter of FOSS apps (that’s the reason I have only one paid app lol) - but Moon+ reader Pro beats Librera in two areas - Librera is pretty slow when it tries to open a huge file, and Librera also can’t download book covers like Moon+ does.