Last time I checked, Franz is simply an electron app. Basically it opens each chat’s own website in an independent tab, isolated tab. It’s not different than opening multiple tabs in Firefox and using Multi-Account Container so that you can log, e.g., multiple accounts of Microsoft Teams.
So if we decide that route, we could simply leverage that:
And either run whatsapp web in a browser tab, or use a dedicated separate browser-app (like the log-in portal).
This would have all the same limitations as running a browser (no logs, no saved photos, etc.)