Your microSD card from your Steam Deck isn't going to work in the Switch 2. SD Express cards (including microSD Express) have extra connector pins. You're going to need a microSD Express card.

This utility needs at least MOS version 1.03. If you are still running an older MOS version, please see this legacy utility version. Flashing VDP firmware from a file ...

Bottom line: The SD Express standard for memory cards initially debuted in 2018 but has seen virtually no use because most devices don't meet its bandwidth specifications. The Nintendo Switch 2 ...