If you able to export your password from Waterfox as .csv file, then you can try steps below to import the passwords to Brave.
- In Brave, go to
brave://flags
- Search for a flag titled
#PasswordImport
and enable it - Relaunch your browser when prompted
- Open Waterfox go to and export your passwords as a
.csv
file. - Return to Brave,
Menu --> Settings --> Passwords --> More icon --> Import
and select the[name of your Waterfox passwords].csv
file and import them.