Must add: I was hoping to achieve all this on a #postmarketOS device. I have pmOS running on a Samsung A3, but was never able to get the modem to work for it to connect to cellular.

Did a hard pivot to this Android setup, and enjoyed the process, but I did so because I could not figure out how complex it would be to get pmOS on this newer Samsung A40.

One issue I did run into was that the newer Samsung was networked locked. I had to apply to Three.ie (cellular provider) to get the device unlocked.

(In retrospect, chances are that this was also happening on the older Samung A3, but tried another sim card from another provider and was not able to get a data connection.)