Require users to join at least one group at sign-up

I can see this has been a popular feature requested in a few threads here.

I’m looking at implementing this, but going about it in a different way.

We need users to select groups as part of the registration process, to populate their experience on our platform, as many categories are only visible if a user is part of the connected group (otherwise the site is too overwhelming for them).

For me the simplest way to solve this would be to redirect users to the Groups page after signup.

Then give users a clear explanation of what they need to choose and why. In the groups page header we can put:

‘Join Groups to Populate your Platform’
‘location, skills, interests, student?, organisation’

I see a lot of posts on how to redirect users after login. I’ve not found any about how to redirect users only after sign-up. Anyone have any ideas?