Yes, there are a few ways to do it. You need to have logged into the Fossil app with an email/password, it didn’t seem to work with “login with Google.”
I used a python script that I ran on my computer that got the private key from the Fossil servers.
https://gadgetbridge.org/basics/pairing/fossil-server/
NOTE: You need to add the private key before pairing with GadgetBridge, if you add it after then it won’t work.
Code money get up get coffee, code monkey go to job.