Did a bit of a drawover for you
Not sure how far you want to go with the muscle model, but my thoughts in more detail:
Some of the thin, tendonous stuff going down to the carpals might be more trouble than it's worth in your case. In an adult lion you might read these shapes a bit more coming through in the skin so it's potentially worth getting the setup solid in those areas but since yours is a cub.. you could save a few iteration cycles by taking those out.
There's a few muscles that have come out very thin in places; this could cause a bit of a headache when it comes to simming skin on top as thin muscles are harder to collide with.. Can lead to trapped vertices,
An overall comment is that it feels like there's a bit too much 'air' between some of the muscles. Not everywhere, but for me, the delts, the back legs and the lower front legs could feel more 'packed'. On this thread https://community.zivadynamics.com/d/444-strange-muscles-behaviour/10 I posted some stuff about anatomy on a big cat. I'd highly recommend checking out that resource for anatomy stuff.
The walk is looking very promising and definitely a good place to start before diving into the shot work.
Looks like line of action is set up for some of the fibers. To my eye, the muscles around the delts are buckling a bit. Feels like they're coming along for the ride, rather than contracting and releasing. Same goes for the tricep.
I'll pause there for now!
Excited about where this is going, looking forward to the next iteration!