from my perspecitve a big: NO!
You call them rest day, because you should rest my friend! Your body needs the time to regenerate, your muscles grow not when you are training, they grow in the time between.
I can tell you from my own experience: I train everyday, or at least i try, doing the handstand. you can do this, because it does not require not that much strength, it focuses more on your mobility and balance.
And another thing: You are at level 4. I do not want to dissapoint you, everyone wants to achieve the skills (human flag, planche and so on), me too, but first of all you need a solid fundament. You have to build up some basic strength, you need to master all the basics (push ups, pull ups, squats, dips, planks).
Level 4 is no level where you should think about mastering the planche. the planche is in general a good example,it requires a lot of training experience!!
I see the muscle up also as a skill, it makes no sense training for muscle up progression if you can not do enough push ups and dips. i really recommend you hitting all the beginner levels and than you can start thinking about human flag, planches and so on.
if you really want to train for the levers, or the human flag. you can include to your workout the exersice "skin the cat", it is a very good exercise which you should do minimum 3x5. after that you can maybe start with the levers progression and so one.
i do train for example with skill training, but not differently i include them as a workout. so on my pull day, i do of course pull ups, but also focus on the tucked front and backlever.
in short: -> master the basics, build up a solid strength, step by step my friend, one skill at the time (of course you can focus on both, however you reach one goal easier than both at the same time)
hard work, good nutrition, enough sleep. that is the key. start with this. than go to the skills.
it is just my personal opinion, if you directly want to start training for the skills, you can do it, but i think at the moment it does not make any sense.