Anyone else here working on flexibility?

I have this goal of being able to do the ‘King Dancer Pose’ (Where I would be able to actually have my arms up and back, and hold on to my foot like that) but I have Zero experience with working towards a goal like that other than the last few weeks just doing stretches on my own almost daily. (Usually after a workout)

When I look at a pic of myself trying, I think that it’s the flexibility/strength of my back that I need to work on... so lately I’ve been starting to focus on that a bit more in my workouts, but I’ve been kind of stuck at this level for a few weeks now.

Any thoughts or recommendations?

Thanks in advance!