It's been a while since support for a new DMM was added in libsigrok. As of yesterday we now also support the PeakTech 4390A multimeter.
This is a rebranded Metex M-3860M (even says so on the device itself, in addition to the PeakTech 4390A rebrand).
It uses the "usual" Metex 14-byte ASCII-based protocol, so adding support for it was simply a matter of adding the respective metadataentries for it in the existing serial-dmm driver.
The initial patch was contributed by Frank Stettner, thanks a lot!