How to build something from the ground up? i will not promote

I don't know if this is the right place to post this, but I've had this feeling for a while now that I really want to build something from the ground up. I have a stable engineering job and I'm grateful for it, but I keep finding myself way more excited about random side projects, startup ideas, figuring out how products could work, shipping things and seeing if people actually care about them. I don't even necessarily need to be the founder. I'd genuinely be happy finding 1-2 people building something they deeply believe in and becoming one of the early people who helps turn it into something real. I know startups are romanticized a lot and the reality is probably stressful, uncertain and messy. Weirdly, that's still the environment I want to experience at least once while I'm young enough to take the risk. Not posting this with a polished pitch or expecting someone to offer me a "founding engineer" position in the comments lol. I just want to meet people who are actually building. If you're working on something from scratch, have an idea you're obsessed with, or you're in a similar position and just want to build something/ I'd genuinely love to hear about it.