1. Export your wallet .json Keystore File, the process is described here:
2. Configure Metamask for the Public Mint blockchain, the process is described here:
3. Via your Metamask browser extension, on the upper right corner, select the "My accounts" section, and "Import Account".
4. On the "Import Account" section, select type "JSON File" and "choose file" to upload the Keystore file.
5. Your Public Mint wallet should now be imported to Metamask.