I've used RealCalc for a few years. I paid a few bucks for the "plus" version. It hasn't been updated in years, but that's fine with me because it just plain works.

I'm using 11CSciCalc on my MotoG7power. It's good (at least for keyboard layout and key-function -- haven't had occasion to try out its programmability for compatibility), but without the tactile feedback of the real buttons I have to visually monitor what actually gets entered, so I can't drop fully into the problem domain, not like I can with my HP11C.

It's my HP41CV that basically never gets used. Back when, I wrote a program on it, 'ampsr', to calculate ideals and then find the closest standard-value matches for a three-resistor attenuator network used as the gain-and-offset control of an opamp amplifier; it took 16 minutes for my HP41CV to arrive at the answer, and that was just selecting among the E24 "5%" standard-value array. My later Perl version, by comparison, is all but instantaneous even working with the E96 array and running on a 400MHz box. The HP41CV's programmability was great for its era; not so much, now.

I'm very happy with CalcTastic, though it's not been updated since 2018 it still seems to work just fine.

https://play.google.com/store/apps/details?id=com.shaytastic...

I've been happy with realcalc, nice relatively basic scientific calculator. Or emu48 in 50g mode for when I need something more advanced.

I've been using Droid48 for maybe a decade now, it's very robust. Recently started playing with Emu48 with hp50g skin as well.

That's what I ended up with as well... looks pretty nice. It'll be interesting to see how much of my 11C experience transfers over, at least, that which I remember in the first place. I've never lost RPN (mainly because of good old dc), but the programming is a different story.

I've been using RpnCalc by Edward Falk on Android for many years without complaint. Last updated 2017.11.