What surface are your exterior walls? Vinyl siding, for instance, is easier to penetrate than brick. Is the camera going to be mounted to the outside wall, or some distance away from it? I have a Linksys EA7300 router with a Linksys AC3000 WIFI extender at the other end of the house to power our TV streaming. My only indoor stickup camera is about 3 feet from the router and shows about -50db or better. My other cameras are mounted on exterior walls around the house, and all show -55-62db. The back door camera, which is closest to the router, shows an RSSI-46 in the app, while the furthest away shows an RSSI-65. All of them work fine. There is occasionally a 30 second or so delay between an alert and the time that it shows up to be seen in the app, which I assume is due to the lag when uploading to Ring.
I would download a WIFI Analyzer app on your phone and walk around near your router and then where you plan on your outdoor camera to see what signal loss you see. If it’s too much, you might consider adding a wifi extender near the side of the house that would be nearer to your camera.
(Personally, I wouldn’t let the doorbell warning bother me too much. I installed one for my daughter on their front door, 15 feet from their router, and she gets those from time to time even though there is no problem with her signal. I also recently installed a Ring alarm with an outside camera, and she also has no problem with it. )
And the solar cells are the way to go for an outside camera. Hopefully they have upgraded the installation instructions and the app interface by now to help with that. It still wouldn’t hurt to search through the forums to see how others dealt with installation previously. I had to make a mounting bracket for 2 of mine to get them above the gutter at the roof line on the shady sides of the house so they could see the sun, but well worth it. I haven’t touched my cameras in 4 months of winter weather.