Ironically, on my Xperia 1 VI (which I specifically chose as my daily driver because of all the compromises on flagship phones from other brands) I had the only experience where I actually felt like a smartphone feature based on machine learning helped my experience, even though the Sony phones had practically no marketing with the AI buzzwords at all.
Sony actually trained a machine learning model for automatically identifying face and eye location for human and animal subjects in the built-in camera app, in order to be able to keep the face of your subject in focus at all time regardless how they move around. Allegedly it’s a very clever solution trained for identifying skeletal position to in turn identify head and eye positions, it works particularly well for when your subject moves around quickly which is where this is especially helpful.
And it works so incredibly well, wayyyyy better than any face tracking I had on any other smartphone or professional camera, it made it so so much easier for me to take photos and videos of my super active kitten and pet mice lol
I totally agree with the AOSP-like ROM and I love it so much too, especially since Sony also makes it super straightforward to root (took me less than 10 minutes) with no artificial function limitations after root (unlike the Samsung models where you can even root at all), so a highly AOSP-like ROM also means a lot of the cook OS customization tools originally developed for Pixel phones, where most of such community development efforts are focused on, tend to mostly work too on th Xperia phones :p
For side-loading Sony native apps from other models, I tried the old pro video recording app from previous gen (the Cinema Pro) on my Xperia 1 VI just for curiosity (since the new unified camera app with all the pro camera and pro video features included in a single app is definitely an usability improvement lol), and it worked fine, so it might work too if you side-load the new camera app onto your older model, feel free to DM me if you’re interested to experiment with this and I can try the various methods for exporting that app and send to you.
Although Lineage OS is not yet available for the gen VI model since it only came out in 2024, however the previous gen V model got its first Lineage OS release in around September, 2024, so it might not take that long to get Lineage OS for the gen VI model :D