So this is a pretty short list but here’s some sapphic graphic novels!
The Lumberjanes series
Honor girl (technically a “graphic memoir”)
Blue is the warmest color (I haven’t actually read this one but my friend told me about it and it sounds great!)
One hundred nights of hero (might be kinda obvious?)
Princess princess ever after (pretty obvious but it’s really good)
Also:
Fresh Romance (an anthology, really cute high school romance story)
Bitch Planet (prison for woman who don’t fit society’s standards of womanhood)
Fun Home (another graphic memoir, inspired the musical)
DC comics bombshells (lady superheroes but in WWII, everyone is gay basically)
Young Avengers v2 (no sapphic relationships but again everyone is gay, features America Chavez aka the love of my life)
bonus: The Secret Loves of Geek Girls is technically not a graphic novel, it’s a mixed media anthology with memoirs about romance by different women, lots of sapphic stuff in that
Gonna have to correct the Fun Home listing. The musical is inspired by the graphic novel. :)