It would be interesting to create a jobs-and-resume app on activitypub, but it is very fraught. In particular, there is no privacy in the fediverse, since servers gossip the posts/DMs/toots/whatever around the whole system (probably???). This would mean that if you started applying for jobs while employed, your employer would be able to eavesdrop on messages -- even if they were end-to-end encrypted, just seeing that you have been in contact regularly with a competitor would be enough to cause trouble. I think this is something to be revisited in the future once the w3 has had some time to mull over how to add DMs and stuff to the protocol.
I tooted about this, and I got a suggestion to build a "professional linktree" instead, which is also an interesting idea.