There is a danger in learning only the strength elements of gymnastics: Sure levers, muscle ups are cool, but so much of the lessons of gymnastic rely on you understanding how to efficiently use gravity, angles and lean the achieve movement.
To learn the muscle up, you must at some stage use the kneeling muscle up drill: but there are 2 set ups. A crude, arm strength builder, is with the knees under the rings where the pull is straight up. This is a great starting point as it improves arm strength, although the ideal movement pattern isn’t trained. Another variation of this exercise moves the toes under the rings and brings in a larger lean back. Here the pull is, in theory. to the hips, meaning the shoulders have the space to be swooped over the rings by a drop of the feet. This drill requires no break at the hips. Ill try and do a video later.
in the meantime, think about what a lean in certain circumstances can achieve