@gbryant correction for the last two podcast, L5's m.2 slots are for communication m.2 cards. Sebastian Krzyszkowiak from @purism has commented that the m.2 slots are not usable for cards that do not use communications (with simcard and/or antenna).
Check out the two tables in "Form factors and keying" at https://en.m.wikipedia.org/wiki/M.2
Love your show and podcast!