Everything in computers is encoded in binary with 1s & 0s.

But to answer, the extension doesn't give your secret to apps at all.  The other way, apps will say to the extension "sarah wants to post this recipe, please 'sign' it so I can post it to the relays and they know its from the right account"

The secret never leaves the extension.  Once you paste the secret into the extension to store it, you really shouldn't paste it into anything else (except another trusted thing like amber).