Essentially looking for a shared drive that family members or friends can upload files to without having to make individual users / accounts
Anyone know a good way to do this (self hosted or another service if Foss / private)
Nextcloud is a nice centralized system for that, you can setup shared folders that appear as a weblink that anyone can upload to, but it would require someone (likely you) to set up and maintain a LAMP stack application.
Otherwise if you want a simpler "share files between PCs" kind of application then Syncthing would be great for that. Install it on both PCs, link them, then setup a shared folder. The contents of that folder are then mirrored between the pcs.