I use surface pro 3 with pop os, basically u can install latest ubuntu and install this custom kernel. https://github.com/linux-surface/linux-surface
And staying on Wayland it's handle much better multi touch fingers especially on gnome which feels like designed for exactly such devices and gestures feels and works much than on windows my fav one 3 finger swipe between virtual desktops
T launcher working fine under linux since it java just find and download it as .jar file
But i also recommend higly recommend https://llaun.ch/en it was original tlauncher laucher, more details
https://telegra.ph/The-True-Story-of-TL-05-21
Developer even publishing source code of his laucher.
But u need to download from ukrainian,russja,belarusia or other countries cause for most europe couries it gonna show DCMA banner from mojang,in other case it will load all files
2.I am using ifuse without any need for itunes i simply copy paste files as it would be android phone i am using it in cli ,but u can try to use https://github.com/Helltar/idevicegui
I am using celluloid or smplayer which is frontend for mpv,mplayer and other,great tool.
U can customize almost any shortcut u want
About distribution i like linux mint cinnamon for me it feels quite polished and also using arch linux with kde,but i don't think it's for u,at least for now.But at the same time arch have the biggest repository of any kind of programs comparing with other distros + aur .i am running it on everyday bases and mostly everything just works except if nvidia driver break something from time to time.
I am personally not exicted about using arm on pc/laptop all because situation with them can repwat situation with phones where we have locked down devices without ability to unlock bootloader and hug problems with drivers as sequence. Also there no uefi with ACPI so each distribution should be custom build to exact laptop because of operating system should know about installed hardware in laptop/pc in DTB file,i would prefer stay on x86 long as i can and maybe risc v cpus gonna change this situation.
You don't need a doorbell camera, get a regular camera instead.
You need an app which will receive events from a doorbell via a server to receive data to interface with the app. Both of those things need to be owned and operated by someone to be approved for use on the app store. That's why a custom open source of doorbell as you envision it doesn't exist and never will.
I have 3 elderly people for whom I installed Linux Mint, they have been using it for 5 years now. Without any problems.