This Module is currently available.
A 4 input, 1 output audio mono mixer (i.e. not stereo), with individual channel knob for levels. There is also a 4 channel mixer (B1 – B4) without control which can be used for mixing CVs.
https://wiki.aemodular.com/pmwiki.php/AeManual/MIXER44
These merchants probably sell this module. Huh?
Included in 136 Racks, 78 are public: