You could rig up some rPi's, but then you gotta maintain everything yourself. Weatherproofing is probably a PITA too.
rPi don't have an open source firmware either.
And no decent image sensors.
The ones they sell aren’t great, but you can - with a bit of perseverance as it’s non-trivial - connect CSI-2 MIPI to a Raspberry Pi, and use any image sensor that supports that. Which includes a ton of great Sony CMOS sensors.
Are you sure? My info might be out-of-date, but a few years ago the MIPI support was in some propriety Broadcom firmware. So your choice was basically the ~3 sensors on official RPi camera boards (although people would sell you things like different lens mounts etc)