Soldered RAM changes nothing for Linux.

No impact. Linux doesn’t care if the RAM is soldered or socketed. The memory controller is the same chip either way, and driver support is identical.

The only real difference is repairability. If a soldered RAM chip dies, you’re replacing the whole board. But that’s a hardware problem, not a Linux compatibility problem. The OS just sees memory at certain addresses and speeds.

So if you’re picking a laptop for Linux and the only option is soldered RAM, don’t worry about it. Worry about the WiFi card or the GPU instead—those are where Linux driver hell lives, not the RAM.