well, i don’t own one currently, but pics i saw from the om5 looked good to me this article has some low light examples for the om5 and i cant remember it being a point of critic when i was reading up on reviews when i was looking for a camera, so i’d guess you’ll be fine.
i actually bought a lumix s5ii, a full frame camera, and regret it sometimes a little bit due to the weight, bulk and price of some lenses and i’d probably buy a om1 in retrospect.
fixed lens cameras are a relatively niche thing nowerdays, despite the hype around thr fuji x100vi and the rico gr3.
i’d look for a micro-four-thirds camera like the om system om5/olympus e5. The micro-four-thirds sensors are very good, despite being smaller, the system offers a ton of good glass that tends to be lighter and smaller than aps-c or fullframe equivalents, so very backpackable.
for receipts and such paperless ngx is good. that won’t track your repairs or inform of you of likely maintenance problems, but that and a spread sheet sounds like a good start.
look into local dns servers if you want multiple machines to use your local domains if you only want a single windows or linux (and probably mac) computer to use the domain to access a specific local ip an entry in your etc/hosts file would be enough
https://github.com/docker-mailserver/docker-mailserver should be able to do it.
if i remember this in 6 weeks i’ll check the setup at work.
Nikon itself offers an F-Mount to Z-Mount adapter which should retain autofocus and stuff like that on many lenses. the adapter is named FTZ Adapter. The z mount is nikons mount system for their mirrorless cameras.
So do some reading to find out if your lenses will work with it and the camera you are interested in and then decide if you like the lense enough to invest in the adapter and a compatible body.