Didn't watch Gravity Falls but as far as I knew they were confirmed gay, admittedly in the finale.

There was also a gay cop in Onward

I also don't agree that Finn was a minor character, he was a regular focal point in two movies much to the annoyance of the same conservative groups.

I'm by no means suggesting Disney is anywhere in the neighborhood of acceptable. Gay characters have a tendency to be tiny roles or unpromoted movies (I watch a lot of movies and I hadn't seen anything for Strange World before it released). I'm just saying "never" is probably inaccurate for modern Disney.