The success of the 90 degree lens on the Firefly 8S and 7S meant that I started to look for other cameras that are also sold with narrower angle lenses. While the firefly “non-distortion” versions seem to be quite popular, and so suggest that this may become a more common option, at this point almost all action cameras have 170º lenses.
The Gitup Git2p also has a 90 degree version, but this camera is the same price as the Firefly 8S and still only has the Novatek 96660 chip, so isn’t capable of native 4k. While it does use the Panasonic MN34120PA sensor (which is reputed to perform well in low light), the newer model (GitUp G3 Duo) now uses the Sony IMX117 sensor, as used in the Firefly 8S.
At the time of writing, there do not appear to be any other “non-distortion” action cameras on the market.