It is here, the Instance Picker!
You can help your friends find a home on #Mastodon, by directing them to two places.

If you also want to provide them information about what Mastodon is, Joinmastodon.org is the place
https://joinmastodon.org

If you want to just help them pick an instance, @TheKinrar 's instance picker can be found at
https://instances.mastodon.xyz

And a feedback thread is here:
https://discourse.joinmastodon.org/t/feedback-instances-mastodon-xyz-thread/401