Why no local mod installation possible ?? It would be the better way to permanently install all the mods on the built-in SSD storage as with the Farming Simulator 2019 than always this online dependency !! Snowrunner only runs at Permanent Online , nothing works without a network !!

SpintiresMod allows that (can verify this for Mudrunner), but I can't get it running on Snowrunner, even though it's advertised to work with it. That's a third party modloader though, so neither Saber, nor Focus have anything to do with it. Plus, you can't reasonably blame them for not officially supporting some hacky third party tool.
The most up to date version is on a russian website (stmods.ru), it's just I don't speak russian, so I usually dig through mods requiring it (the BT361A for example does, that modloader also delivers a framework for treaded vehicles) and hope for the author to include a link. The tool itself also has english localization. Idk, maybe this works as a temporary solution for you. Keep in mind that running that tool basically means, if you crash, you're on your own. You can always uninstall it and return back to normal, anyway.