USBc will be problem on an iPhone 11, and I don't remember iOS 15, much. I had to look up "sneakernet." It apparently means putting stuff on a drive and then "walking it," apparently wearing sneakers, over to the other device.
AirDrop is really great, but AirDrop is made for doing a few pictures at a time. So it's probably best to divide up a big bunch into smaller groups. This
How to use AirDrop on your iPhone or iPad - Apple Support
doesn't discuss a maximum number, but we've seen people have trouble with doing lots at once.
If the sender is using iCloud Photos, then a shared link can be set up:
Share photos and videos with an iCloud Link on iCloud.com - Apple Support
I tried just connecting my iPad with my iPhone-- I got "Trust this Computer," but they don't appear in each other's files app. Darn!
Probably DropBox or the equivalent is one of the better options...