No use cases for this so far.

Mobile service quality is defined by the baseband, which is an immutable blob to the OS. I phone rarely and currently use my old LineageOS phone for it.

I’ve got a support case for my Pixel 7a open due to potential battery issue. If I return it I will buy a different, bigger (6.7") Pixel model. My new Pixel tablet is doing fine so far.

I use tablets to read things when lying down, so notebooks don’t fit.

Matrix (Element), Signal, Telegram. Other stuff probably requires Google services which I don’t use on the tablet. Phone has Google services, but I don’t really use it for messaging other than Signal.

I’m on GrapheneOS on tablet/phone for time being, but I’m fine going back to a dumphone and a Linux or BSD tablet or convertible.

Great writeup.

How much is a kWh in your parts? Noise, ambient temperature? You can buy very decent refurbished Lenovo tiny PCs with some 16 GB RAM and 6 cores and half a TB SSD which will run Proxmox and are low power and noise. You can go multi-node Proxmox later if you want to expand. k8s and related are also an option.

DIY few kWp solar payback is about 2 years.

In Germany consumer power is something like 0.4 EUR/kWh, so economics of running power-hungry hardware might be different. Solar PV might change the equation once again.