This app was mentioned in 15 comments, with an average of 2.53 upvotes
I'm well below your level but I'm a big fan of Tsumego Pro. It comes with a decent amount of problems and you can also buy additional packs of 300 problems for $1.50 or so each. I'm not sure if the "advanced" level problems will be too easy for you though.
Tsumego Pro is good for practicing your tsumego. It comes with a bunch of problems out of the box, and then you can buy a ton more for like $1-2 per pack. Each pack has around 300 problems from beginner to advanced levels.
For tsumego, Tsumego Pro. Also, there is apparently an impostor app with the same name. :-\
For playing, Go Gridmaster.
I haven't tried very many apps yet, but for Problems I've used Tsumego Pro:
https://play.google.com/store/apps/details?id=net.lrstudios.android.tsumego_workshop
I like its daily problems and it has a decent amount of free problem packs to work on.
Maybe you haven't progressed because you haven't read a book that gives you a good foundation for later progress.
The Learn To Play series is very user friendly and I am sure that by reading the first 2 books you will become at least 15k.
On that same website you can buy more theory books in .epub format. There are also Tsumegos (Go Problems) books, but you can find those for free online or in the Tsumego Pro app
I've been having a lot of fun using the S Pen on tsumego and go apps. Placing the pen down and picking it up again has a similar tactile feedback to picking up a stone making the action more thoughtful than just putting your finger to the glass.
I use Tsumego Pro and Go Free currently, but I'm always open to suggestions for better go apps! Particularly ones with good AI.
If you don't mind only getting 2 easy, 2 medium and 2 hard problems per day, Tsumego pro is free, and the problems are pretty good IMHO.
This is what I have in my go folder.
Tsumego Pro (Go Problems) for problem solving, there's also daily challenges.
"Go" for AI games, the app claims to be as strong as 3 dan, with adjustable difficulty. There's a free version too but no 19x19.
Lazy Baduk, analysis tool using leela zero. Not sure if leela is dependent on your phone's hardware with this app.
Online GO is still being developed, it's a client for online-go.com. You can only play matches; tutorials, tsumego, and live games aren't implemented yet.
In case you are looking for more than just online play:
Tsumego - might be worth buying more sets though - they are not expensive
Go Dojo - predict a move in a professional game, kind of fun :)
Hactar go - seriously hate the interface, but has one of the more interesting tsumgeo sets, including middle game tesuji and endgame problems.
Crazy stone - offline play against a bot or a human, should be about 1d level strenght
IMO, the most portable option to train without playing online, would be reading books and doing tsumego. Playing games isn't the only way to improve, as just thinking and reading about Go can make a large difference. Doing things in your own time also makes it great for travel as you can stop whenever you need to take care of something more important. For 10k, I would recommend for books:
Physical-copy The Basic Principles of the Opening and Middle Game
Online-copy Shape Up!
And depending on what mobile devices you have, for tsumego:
Brettspielapps? Tsumego zum Beispiel oder auch Schachprobleme.
I use tsumego pro throughout the day.
Thanks a lot for the list. What about the Tsumego app for Android ?