To put it in perspective: how do you clean the lens on your phone camera?
Phones regularly get held by sticky/sweaty/dirty hands, put in dusty pockets, placed on dirty tables/desks etc, whereas your drone camera very rarely gets touched by anything other than fairly clean air, so the requirement for cleaning your drone camera should be significantly less than a phone camera, unless you're into touching the camera lens, flying low over breaking ocean waves, through clouds of mosquitoes and landing directly onto dusty ground.
A single wipe with a clean shirt sleeve does the job for me 99% of the time for my phone.