i'll bring up "important info" (im assuming this means their main anime storylines) first. it's not much

i would say only mygo's intermission at bandori 12th live is fundamental, i have it subbed here https://b23.tv/BA6sOFy. fun fact, it was even mentioned as part of the "watch order" in the movie pamphlets!

we have the manga coming https://comic-growl.com/episode/2550912964982649376 and the movies should... EVENTUALLY get on bluray. hopefully

for ave mujica, they have their intermissions here https://docs.google.com/spreadsheets/d/1DBK-rJRVUkEytYobidfWmVr178RDZri4raGyLJTrq7o/edit?gid=0#gid=0. everything up to 0th is its own storyline not involving the dolls

thats the "important info". nows the fun part...

mygo has individual character covers! which are supposed to Say Something about who sings them. mostly they're tomori songs. and she's sick in the head. but i like taki's shiori and raana's teenage riot for characterization too https://youtube.com/playlist?list=PLUFFl4hYd1R3DbWVEUf1Nk6LUN8f-yjwX

they have short intro/QnA vids as well! i think its a fascinating relic from their earlier era tbh and its interesting to see how its aged https://youtube.com/playlist?list=PLUFFl4hYd1R1Pq4A_W2UmVbw9-wLCETFb

there's their weekly radio show, Maigo Center. it used to be purely in-character but they have seiyuu episodes now as well. a lot of the early episodes aren't subbed unfortunately but one day maybe(?) i'll get to that... https://youtube.com/playlist?list=PLUFFl4hYd1R0SQPSCAqPVuT5F2By4pqO7

in garupa, so far they have two unit events and two mixed events
breathing next to you (taki+raana) https://bestdori.com/community/stories/130897/
the colors muddled with the raindrops (soyo+tomori with some taki) https://https://bestdori.com/community/stories/144007
sakura circring (mygo meets the rest of the cast) https://twitter.com/dewdroppes/status/1769358187260428604
the scent of our blend, wafting by the window (taki works at hazawa coffee for a day) https://bestdori.com/community/stories/170215

i have their bday cards translated in my directory https://tinyurl.com/dimadirectory
...i realized i dont have anon's bday story linked there. whoops lol https://twitter.com/maigosusume/status/1833004852001259698

there's also three dreamfes stories (two upcoming)
raana df (untranslated? afaik)
soyo df (upcoming)
tomori df (upcoming)
they're basically two-part character studies

for avemuji...
refer to the masterlist above.
read the mujicarni article,
watch the lore videos,
watch prelude to 0th,
read the interviews,
listen to the songs and read the lyrics,

and welcome to the world of ave mujica :)