Did perl5 to perl6 actually happen? I feel like perl mostly fell out of favor along the way.

No. Perl 6 was renamed Raku (?) so people wouldn’t be confused that the 5 line was continuing development.

Basically, to the degree I understand, the language was effectively forked into two.

Disclosure: I'm not intimately familiar with all this.

I think Perl5 was originally planned to be replaced by Perl6. Then Perl6 took much longer than anyone expected, and kinda ended up in a different place. Perl5 was re-anointed as the once-and-future Perl, and what had been Perl6 became Raku.

If I remember correctly, somewhere in the middle of all that there was talk of running Python (and other languages) on the new Perl6 VM.

It's a good example of a migration that mostly didn't happen.