Oof it's gonna be quite a read.
There is the plus girls debuting this year, who are under the creative control of Min Heejin and Bighit but managed by Source (They also say something about Min Heejin's label but idk what happened to that). These girls have been selected from the plus auditions back in 2019 with the line up fixed in 2020. They are mentioned to be a "blockbuster group". (I have absolutely no idea what they mean with that).
Then you have the suspected Izone subunit/PD48 group which is group reported by ONSEN to be debuting next year, rumoured to have 5 members most being from PD48 series. They will likely be under Source without the involvement of BH.
Iland GG, debuting next year somewhere.
Bighit has a collab with one of the members of LDH group, Exile. A very successful Japanese boygroup. They will be the one making the music for the group but the girls and management will by the LDH member.
Now I put maybe 5 because I'm not sure if that LDH group will count as their "Japanese GG" or if they are still debuting a new GG under their own Japanese label.