Selfhosted

I've been running Protect since around Christmas on a UCG Fiber with a 2TB SSD, with a single G6 Turret recording 24/7 full 4k quality. As of right now, my recording history goes back to January 19th, or about 25 days. Based on that, rough napkin math would put 6 cameras at around 8 days of continuous FHD footage, by my estimate. Protect has per-camera settings that allow you to change retention policies, as well as choose between event-based recording, continuous, or adaptive, where it reduces recording quality for the uneventful majority of the time, then records full quality during events. These options would meaningfully increase recording storage time.

While I'm currently only running a single Unifi-branded camera, I have previously added four TPLink Tapo wifi cameras to Protect as well, though you have to enable an experimental setting to add third-party cameras.

Protect allows you to set up detections based on a wide range of events, I believe partially dependent on what camera model you use and what the camera can process internally. My G6 Turret can detect motion, people, vehicles, animals, license plates, faces, burglars, packages, glass breaking, sirens, car horns, dog barking, talking, etc. You can set motion zones to filter areas of the field of view for detections, you can set privacy blackout areas, and you can disable the microphone. Can't compare detections to Ring, as I've only used Google Nest and Unifi Protect. I haven't put a huge amount of effort into managing detections beyond setting a zone so I didn't get notification spam... of which you can set push notifications and/or email notifications per detection type. It's relatively easy and responsive to click through detection events in the app. Don't know how much slower it would be on HDD storage.

As for the doorbell, I've been looking to switch from Nest to Unifi, but I'm waiting for the G6 Pro Entry. Since you can't run Ethernet, have you considered the G4 wifi doorbell? It runs off of 24V AC that's typically already running to the doorbell. If not, I'm sure you could kludge something together in Home Assistant.

As for the interface and wife-friendliness, the setup side of things can get you a bit lost, but the day-to-day usage is pretty intuitive. It's easy to pick a camera and go into the detection history or scroll through the timeline.