I'd say Errant is most similar to a lot of modern manga-influenced cartoons and webcomics with queer creators, so stuff like:
Nimona, She-Ra, Steven Universe, Lumberjanes, Witch Boy, Owl House, Pandora's Devils.
It's character-focused Fantasy comic with drama revolving around people trying to understand each other, it has a mixture of cartoon, indie comics and manga influences to the art, and it has progressive political themes and LGBTQ+ characters. It's about a group of colourful friends teaming up to overcome a big magical threat that's also tied up in a bunch of emotional baggage. It's hard to pick one specific work that's an exact match, but there's a really big readership overlap between Errant and Pandora's Devils on Tapas, so I'd probably pick that as a Comp Title.
....Yeah, that checks out. Modern fantasy setting, swords, bright colours, female main characters with complicated feelings for each other.... yep.