google hug of death
For each number, I mark all cells where I know I can't put it.
If one block, column or row has only one possible cell where a number can be, I put it there and then update all cells where I now know I can't put it anymore.
This algorithm probably isn't the fastest, but it's easy to do manually and it has the advantage that you don't need to backtrack.
I use WSA to run NewPipe on my Windows tablet - it's a bit of effort to install everything, but it works better than using the website in Firefox. I haven't tried it yet, but it should also be possible to use it with Waydroid on Linux.
For a long time, it used to be Square Root of Minus Garfield - I actually got my username from there.
Nowadays, it's probably xkcd.
If you are in the EU, you should be able to force them to delete your account by filing a GDPR request.
Enteignet die Großkarmabesitzer, es lebe die Revolution der Karmaarbeiter und -bauern!