Its cool to see people thinking about how to donate when they can. I think about it as well, and when I have donated I think most if not all fall into your list.
It won’t be as good as native hardware support, but you can buy a device to add wireless charging. It plugs into the phone USB-C and has a short flexible cable leading into a thin (1 mm maybe) wireless charger receiver that can fit inside a phone case
I am in the USA using T-Mobile. Yes, voice calls work. Depending on when the device was shipped, it may require a modem firmware update. After that its a simple install of bm818-tools package, enable VOLTE and then reboot.
Its cool to see people thinking about how to donate when they can. I think about it as well, and when I have donated I think most if not all fall into your list.