The closest thing to foss LinkedIn would be the repos, forums, and chats for open source projects. Some of them have other dedicated channels for jobs other times it’s you know this person and they see you are looking for work and they tell their friends. There is not a drop in replacement for LinkedIn that is open source. The biggest value of LinkedIn is a network effect so even if it did exist not using LinkedIn would make finding a new job harder since you couldn’t find opportunities that are only posted on LinkedIn.

Side note LinkedIn is gross they serve ads in your dms and notifications

I use evolution and it works well for everything besides my work Gmail but that has more to do with security policies than evolution

Cockpit has an update manager built in and has the ability to setup dnf automatic

Veronica explains https://youtube.com/@veronicaexplains