Ooh, sounds like fun. Sadly my experience with PostmarketOS on the pinephone has been a bit too unreliable for me to use it as a daily driver. (Though I'm running it as my daily driver on the pinebook pro and it's been awesome for that.)
Yeah it's a but unreliable for me too -- especially with the battery management.
I plan to turn the phone into a dedicated pihole device in a chrooted arch linux install¹. Given the battery issues², I will probably buy a bluetooth plug socket and use it to the power the phone, where I will then write a little script on the device that manually checks the battery capacity³ and if it's too high, it tells the the plug socket (via bluetooth) to switch off, and if too low to switch on.
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