A while back, I needed a camera on short notice, but I didn’t have a server or any real hard drive space to speak of, so I just used “motion” on a 20 year old laptop, using the built-in webcam. It only saves video when motion is detected. I set it up to send me a Signal message with the video any time motion was detected, using signal-cli from the AUR. I know nothing about docker, but I thought it was super easy for my purposes.

I don’t know what the state of either is on a Sony 10 IV, but the answer is almost certainly Lineage. It’s the more mature project, and it’s way more likely to work. And at the risk of getting on a high horse, Lineage’s unfortunate but necessary (if you actually want your phone to work) reliance on proprietary blobs is already bad enough; I certainly wouldn’t trust my privacy to a project like Sailfish, which I understand to be partially closed source.