I want to grab the phone to try out Ubuntu Touch but I don't want to contribute to e-waste if I can't get past the FRP.

Any advise?

Its already ewaste.

That's very helpful, thank you.

Now, I can only help part of the way but maybe this will get you started…

If you can plug it into a computer, and the computer sees it…theoretically you should be able to flash it.

If the FRP is on, you shouldn't be able to reset or flash it. Therefore, ewaste. Sorry for the overly terse initial message.

Only if it's bootloader locked.

Otherwise you can flash Lineage

FRP on implies bootloader locked does it not?

FRP isn't triggered when the device is reset via the Android settings app (i.e. not factory reset mode of the Android bootloader). Yet, this implies that the device boots and the user can login successfully.

https://www.guidingtech.com/bypass-google-frp-on-android/

Its an end-of-life product regardless, so it should be recycled. Its not worth carrying around a forever-compromised device, at least not for me. Google offers a recycle program here:

https://store.google.com/us/magazine/recycling?hl=en-US

Won't the android settings app prompt for the login details before reset? (At least in the normal case, the google keyboard bypass seems like it does, but who knows if that still works)

IIrc, it prompts for the lock-screen pattern or alike, but not for the credentials of the Google account.

I've ported Mobian to the Pixel 3a, it can therefore still be used and is a perfectly fine phone. Also, there aren't many other small phones one could use with Linux.

You can port a lot of things to a Pixel 3a, but the firmware has been end of life for years now. At the hardware level, its always vulnerable. The OS alone can not protect you, even if its up to date.

The smartphone is far from ewaste, great jack, with good camera, makes the perfect device for an mp3 player to take along hikes.

As long as it never touches any network ever again and there is never anything personal installed on it ever again then it should be OK. Be sure to rip out the GSM and/or CDMA chipset, wifi, bluetooth, and NFC. When connecting it to another device through USB, make sure that device is offline and ADB mode is disabled. Remove all sim cards as well.

There are much better devices for your purpose than some old ass phone tho

Whatever. Still not a reason to constantly throw hardware away unless you have a specific threat model.

My threat model is anything vulnerable that can access a network should be gutted and smelted down if it has been abandoned from the manufacturer.

Don't throw it in the trash. Recycle the materials instead to rebuild newer better hardware.