it seems like I hit dead end...
multithreaded D2GS needs special PVPGN, but it doesn't work with https://github.com/pvpgn/pvpgn-server
it works only with https://github.com/tesseract2048/pvpgn which doesn't include d2dbs so probably needs https://github.com/tesseract2048/D2DBSDotNet which is for windows...
What could work is https://github.com/pvpgn/pvpgn-server with classic D2GS - if I can apply needed patches...