I feel the same way. I wouldn't classify myself as a 10x developer, but I'm the most experienced and most senior developer at a smaller company and I have no peers, technically. It's good in some aspects because I get to work on secondary skills like mentoring/coaching and such, but it's a step back, technical experience-wise. I consume a lot of technical content like blogs, books, conference records, meetups, and podcasts so I can continue to get the learning I'd normally get from a peer. Side projects also help to a certain extent.

It is lonely because I have no one on my team to go to for different views on most technical or software decisions I make in my everyday work. I like being challenged because that's where a lot of my learning happens.

I'm currently contemplating moving to a larger company (or a more mature software org) where I can have some peers to lean on.