New Mini with external hard drive for photos?

I’m moving to a new Mac Mini that has a smaller internal hard drive. I have 200 gb of photos that I want to store in a photo library on an external SSD. I could use help in checking that my thought process is sound. The process has three stages and I am not using iCloud Photos.

Old mac: MBP 2014 on Mojave
New mac: Mac Mini 2020, m1 chip on big sur

I have backed up both machines.

  • Stage 1 - Moving photo library from old mac to new mac
    • Can I move the photo library here to the external SSD on the old mac and then connect the SSD to the new mac? I don’t know how much the photo library has changed between Mojave and Big Sur
    • Otherwise, maybe I would have to import the photo library from old mac to the new mac?
  • Stage 2 - Photo libraries on an external SSD
  • Stage 3 - Backup
    • Time Machine to backup the external SSD to another drive
    • Arq to backup the external SSD to my normal backup process

Any caveats or holes in my plan?