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At least on Windows it works with Thunderbird.
Only because of the bridge, which is handling the encryption part. That works on Mac as well as on Linux also.
However an integration to 3rd party clients without such an encryption layer (Bridge) doesn't work.
For those unaware, proton mail bridge is a program that sets up a local proton proxy that decrypts the emails then serves them up via a local imap server. Thus the "bridge." So Thunderbird isn't pulling from proton, the bridge is pulling the encrypted mailbox and decrypting, Thunderbird pulls from local unencrypted bridge.
https://proton.me/mail/bridge