The requirements are very lax and even old and ancient USB 2 drives work perfectly well although these are hard to find now. They also run cooler than more modern USB3 types. Another consideration is the length of lead. USB 2 types often had a 1 metre cable, current USB 3 types often have very short leads.
On a practical level pretty much anything available today should be fine operationally. The drive records the data stream directly and as such is very very economical on space usage. A 500 GB offers more space than you will ever need.
As others have said, do not use memory stick type drives. Although these work OK if you choose a suitable USB3 hi speed device it has been my experience that are prone to fail in this type of usage after several months.
Obviously 'at your own risk' but I would think something like this would be fine:
Storite F32 2.5” Ultra Slim Portable External Hard Drive USB 2.0 with 500GB Memory Expansion HDD Bac...
The USB cable has a 'double plug'. That is for use on older laptops etc with limited USB power delivery. You leave the second plug 'free' and do not use it.
