I also don't feel comfortable forcing myself to play according to Grade books, I just prefer to find songs that seem relatively doable online and just choose randomly (at the moment I'm handpicking certain Chopin nocturnes). I just lose interest and just give up when I force myself to do the songs on my grade books in a progressive manner. Will this severely hamper my progress?
Like the others said there isn't a definite answer to this, which means the answer is NOT no. But it seems improbable to me and here's why I think that.
First off, 30 minutes of focused productive practice is a LOT! Most people probably sit at the bench 3 hours to get that 30 minutes. If 30 minutes is what you have, then you know you can't do just what you find fun. You need to practice the right stuff, correctly, and with full attention.
I don't do that. I play some stuff that I need to improve on, and some stuff that is fun. Most of us do that. (IMO there are three modes of playing: practice, perform, play. You don't have time to do practice or play.) But you can't if you want to get to that level on 30 minutes. You will have to discipline yourself.
Second, you will have to work on your weaknesses, and that isn't pleasant either. And, until you get to concert pianist level, you're incapable of fully analyzing your weaknesses. Sorry, but you need a teacher for at least an occasional review, and it sounds like you don't have one. Nor would you do what they say, probably.

video of yourself helps some, but there's no substitute for a good teacher.
You have to practice the right stuff - for your developmental stage and your weak areas, and you have to practice correctly. And that's the third point. If you have a fundamental flaw in your mechanics, then 30 minutes or 6 hours won't matter. You can't get there playing incorrectly. Actually 30 minutes has an advantage here. You'll ingrain bad habits more slowly, and you're unlikely to get a cumulative trauma disorder like carpal tunnel.