Ask HN: Transitioning from DevOps to co-founder/CTO/lead dev?

I'm late 30s, spent most of my career as an SRE / DevOps engineer with a few big names on my CV. Currently working at a startup in a team of ambitious 20-somethings : my role has evolved from DevOps to "swiss army knife" doing architecture reviews, performance troubleshooting, technology direction and generally being the adult engineer in the room, pointing out pitfalls and icebergs to the young CTO/cofounder. I feel my next logical career step is to start something myself. The main issue has been that my core skillset (and importantly, current mindset) is more tuned to architecting, scaling and operating a service than actually building it, which is what is expected of a tech co-founder at first. I should have the background to pick up any language quickly (I did x86 assembly in the 90s, taught C, dabbled with Java/Python/Go), but I lack immediate motivation, time and ideas for side projects. Frontend dev seems overwhelming and backend dev pointless