I'm in the same boat as you so it feels weird giving advice since I'm not far enough to really track my progress but I feel where you're coming from. I have two gigs , an e-commerce business on the side and I'm doing school part time soon too. The side hustle is just starting yet I'm getting close to making back my principle. My plan is to open as many streams of income as I can as fast as possible and I'm only at 3 (or 2 since 2/3 income streams are jobs). Saving money is important too.
One thing that bothers me is time, you have to be constantly aware of it. I realized the importance of it only a couple years ago which is fine, I'm only in my mid 20s. Time will make you want to get this shyt popping all at once but doing so compromises the quality of what you do. I have a system I've been on this year that keeps me accountable of the work I'm putting in on my long term goals. Basically on any given day I have to do three tasks which work on my long term skill to make a "successful" day. This helps me keep accountable of my progress. I can't tell just how well it's working until the end of the year assuming I stick with it.
Your problem is similar to mine: we got a ton of ideas but only 24 hours in a day. If you wanna learn a skill prioritize and work it constantly, I'm talking a daily basis. Trying to do all of them at once will make your preformance shytty in each of them. I've tested this. Focusing will give you better results than being mediocre in everything you try just to impress other folks by saying you do it.
Prioritize your list by what is possible to do now/what you can put off without the door closing on the opportunity then take 2 or 3 to work on the entire year on a consistent basis. Based on your list martial arts needs to be done with immediacy because the door will shut on your physical ability with time. Code can wait if it isn't your career, Music can wait as long as needed.
Writing this made me late for work. fukk you and good luck