Bought a microSDXC card to mod my switch lite later; switch said a system update is required to use it. Next steps?

Switch lite unmodded
Firmware 17.0.1
SanDisk Extreme A2 MicroSDXC 256g

I want to bring my switch lite to a guy in my area who solders on the picofly chip and does the rest. So I bought more memory! I inserted the new microsdxc card and got this message: "a system update is required to use the microsdxc memory card". Obviously I should not update to 20.0.0 right now

I don't know how this might affect anything, if it's a big problem or not, and I really don't want to cause a headache for that person or waste their time. That's why I would appreciate any clarifications and recommendations from you all! Huge thanks