This app was mentioned in 8 comments, with an average of 2.75 upvotes
tsumego pro is very nice for problems, for games i think Go (https://play.google.com/store/apps/details?id=uk.co.aifactory.go) is the best for a beginner, cause have a button to help you to understand the situations that usually a beginner struggling to read
The one I use is just called go, I really like it but you have to pay 1 or 2 dollars of you wanna play 19x19 on it. The "go free" does not have more than 180 moves on a 19x19
https://play.google.com/store/apps/details?id=uk.co.aifactory.go
I feel you. And yeah, I hate ad-supported software and pay2win BS. All of the games I listed above are either paid (one time purchase) or free (as in beer, no ads, no freemium). There is an ad supported version of Go, but ads suck and it's like $3 for the full non-ad version.
LinkMe: Chroma Squad, Icey, Scribblenauts Remix, Door Kickers, The World Ends With You: Solo Remix, Go, Spaceteam.
Maldita Castilla has its own site, it's a sideload game.
Edit - the bot linked the free ad supported Go game. Paid non-ad supported version is $2.49 and found here
I personally use Go Pro, It's not the best app, but I still can't beat it so that's enough for me. In fact, in this app the level of difficulty is not precise at all.
I, who am between 9 and 8 kyu, can consistently beat the app on 1 kyu difficulty for the 19x19 board, 2 kyu for the 13x13 and 4 kyu for the 9x9.
I haven't done any comparisons, but I am content with the app I have on my small tablet. It's name, creatively enough, is "Go", and it's by AI Factory: https://play.google.com/store/apps/details?id=uk.co.aifactory.go
I also use the KGS app, which works well. It hasn't been updated in forever, but it has the basic functionality you need to play or spectate games https://play.google.com/store/apps/details?id=com.gokgs.client.android
I also recently installed the Tygem client. Unfortunately, it hasn't been translated to English the way the iOS version has, but I was still able to figure out how to spectate games. I wouldn't recommend it as my first choice, but I have had fun watching some pro games on there: https://play.google.com/store/apps/details?id=com.tyo.lite.tygem
I think this one is good, but I've only used it on my phone, not a tablet: https://play.google.com/store/apps/details?id=uk.co.aifactory.go
Thanks! This is the one I played: https://play.google.com/store/apps/details?id=uk.co.aifactory.go