Steve Gibson recently created a small utility to test USB drives to see if they work and actually give you the store space they claim.

https://www.grc.com/validrive.htm

It does have a micro SD card slot. It is also possible to replace the main M.2 drive with a larger one, I have 2TB in my Steam Deck.

I regularly take nail polish and paint over these infernal LEDs in layers until they are at a brightness that I find acceptable. Red are not so bad, but blue LEDs area nightmare. I have a cheap Chinese headlamp were the blue battery indicator is brighter than the red led for illumination, and the blue reflects off my glasses into my eyes.