Interestingly I was also an Ubuntu Touch user and minor contributor for some years until the demise of 3G here in the USA some years back, and sadly UT still doesn’t have a usable VoLTE solution. I also played around with Droidian, postmarketOS, Pinephone w/ Mobian, Arch, etc. but then moved to /e/ and Lineage4microG as I needed more reliable call functions from my phone 
Where /e/ left me disappointed was in their hard forks of apps that then didn’t remain updated but made it hard to use the upstream alternatives at the same time. I attempted some contributions to their forks, but it was not easy to do with their structure (no ability to submit a PR for example). I feel they don’t have the capacity to be good stewards of the forks.
Similarly, their nextcloud implementation still remains offline nearly 6 months after going down due to hardware monitoring neglect. I guess I should also note frustrations and limitations I had with their bliss launcher, and the slow upgrade cycle meaning they just now are to an Android 14 base with their “U” series just coming out recently, whereas iodé is already releasing A15 based builds.
So, the “KISS” philosophy sort of broke down when I was realizing, “i want a working notes solution”, “a working nextcloud solution”, “a working app store”, and “an updated system”. Adding those things to /e/ made it more complicated than having an cleaner slate that I could add my preferred options on top of. Using iodé means I get a more technically sound foundation, the upstream apps so I can directly support their development and use, and I can add my own data solutions on top (I use selfhosted immich for photos, jellyfin for audio, etc) without having to shoehorn it into a KISS system that in the end was wasn’t so KISS (again my opinions only) when technical shortcomings left it as a half solution.
PS: I do run Mobian on a Surface Go 2, it is really good and is my daily portable productivity device. Phosh seemed the best of all DEs that can quickly switch between “attached keyboard mode” and “touch only mode” (detached keyboard). But of course give some tries to different distros and DEs to find what fits you best.