For what it's worth, I'm 100% a nihilist, it's absurd to me that there is some inherent meaning in life. Who tf am I to say I know the meaning to life??? BUT I also recognize that I'm alive, as is everyone able to think that thought, and we might as well do something with it despite this. I think everyone contrives meaning in their own lives, and THAT. IS. OK. That itch for meaning needs to be scratched, I live as a rule utilitarian primarily, even though I accept this worldview as one I've contrived for myself rather than something inherently right. If you've got a kitchen full of ingredients, and there's not outright purpose to the "right" thing to cook, it still seems to make more sense to scramble an egg or two, than to demolish the kitchen over the notion of a lack of inherent meaning.
I achievement hunt in video games, sure as heck not because it's the most enjoyable way to play a game (some are annoying and hard) but because I also struggle with feelings like yours, and when I get that little ding, it feels like I've done something (I know I haven't!) but it feels like I did, and that's nice to scratch that little "I did a thing" itch. It's okay that it feels nice, even if deep down I know it means nothing. Crap, so what? Same thing when I finish a book, finish a puzzle, watch a new movie, etc. Everything else means nothing too! But it doesn't do me much good to dwell on that, and so I plod along for my next little ding. Sometimes that ding is the thought that "damn, this subway sandwich, is fucking bangin". Sometimes that ding is getting a chuckle out of how stupid life is (I recently won a costume contest at my work I joined over Zoom. I planned to just watch, and as a dry stupid joke I pulled the lampshade of my lamp, plunked it on my head, and said I was a lamp. I promptly won a vote, and a gift basket to the chagrin of everyone who actually tried on their costume. If that's not some stupid good shit to live for I don't know what is.)
Sometimes that ding (and get this) ISNT EVEN FUN. That's also okay. I often say satisfaction, is more important to my mental health than actual happiness or fun. THIS IS NOT THE CASE FOR EVERYONE, GIANT DISCLAIMER but this is the case for my particular brain. When it's hard to be happy, or smile, the feeling of "hey, well at least I beat that hard level today" sometimes is enough to feel satisfied that I did something today even if I was banging my head against a wall a bit to do it.
My hobbies aren't important, there isn't an inherent meaning in my life, and perhaps I'm not important (who tf decides anyways though?). But I'm here, and I'm going to at least scramble a god damn egg, because someone built the kitchen so I might as well get cooking and see what happens.
I hope you open that fridge and scramble some wicked fucking eggs man.