[throwaway-9320]

Fan cooling a Raspberry Pi 4 is such an odd thing to do. You are essentially taking one of the pros of the Pi - quiet and reliable operation - and replacing it with a moving part that will not offer too much benefit and will eventually wear out or start having issues.

[willis936]

As someone who uses pis and MCUs, I don’t find anything that relies on a micro sd card to be reliable.

[vardump]

You can USB or network boot a Pi. Also in my experience over 9 years: just don't use Sandisk cards and you're fine. Samsung (Pro|Evo) branded cards have worked for me.