Is raspbian-bullseye-arm64+aml-s905x a 64 bit OS?

My previous point was more based on the Idea you were going to “DL” a raspbian image that is less functional than the one provided.

No, if you look at your original post, you just asked two questions that lead me to believe you wanted to use other images. Using the abbreviation “DL” only made it more confusing. Then you “DLed the distros”? Which ones? How am I to know? It sounded to me like you wanted to to use a stock debian or raspbian image for some reason so I figured those were the distos you “DLed”.

In any case, I was only trying to help, I’m sorry if I misunderstood. On that note…

The functionality you’d be missing are things like the libre-wiring-tool and some GPIO functionality. I’m not sure specifically, because I’ve not tried. It’s all open source, so there’s no reason you can’t DIY install anything on any distro, but the same applies to your radio software too.

This guide is kind of light on details, but I think it’s what you need to flash the bootloader and use other distros:

I’ve also used Armbian on a different board, and that’s pretty slick. I’m not sure what packages are available, but they put out an image specifically for the potato too.