How to Integrate Slack & WhatsApp on Fedora Guide
How to Install WhatsApp and Slack desktop Chat Messenger Client in One App in Fedor 36/37/38/39/40/Rawhide GNU/Linux desktop – Step by step Tutorial.
And to Install WhatsApp & Slack Client on Fedora you dispose of some cool Alternatives:
Especially relevant: currently Ferdi is the only completely Free alternative, and so I listed them in order of my Personal Testing Preference.

WhatsApp & Slack Client Fedora Installation Guide