ModDB has a (very) small subsection for SPG:Warlords:
http://www.moddb.com/games/starpoint-gemini-warlords/mods

The game itself has a Mod folder already included, along with the following words of wisdom:

"Each mod needs to have a mod folder and a same-named definition file (.sgwm).
The Mod Manager is used to create the mod archive (.sgwma) that is loaded and used by the game.
Please refer to the dev-blog ( www.lgmgames.net/web ) for more detailed instructions on modding Starpoint Gemini Warlords."

So, insert Mod into Subfolder, then select the Mod in the Launcher.

Now, in regards to Steams stranglehold on mods via the sweatsh...err, workshop, that's something I can't solve for you.

That's up to modders really. Another way is to download all the mods from Steam then upload them somewhere and put the link here. But then on every update someone would have to do that all again.

Can't make any mods working so far; tried to to put .swgma files onto Mods directory and and into folders named after those files inside Mods directory but Launcher can't see none of them. Do I need something more than files listed in MODDB?

P.S. Fixed by deleting broken mod; be careful what you put there Comrades.

Outdated or broken mods can lead to weird game behaviour or even crashes. unfortunately, that's not in our hands. :(

You can just use this online tool to download Steam workshop mods, then just install them yourself:

http://steamworkshopdownloader.com/view/935011706

It appears to download sgwma files from the SPG:Warlords workshop, so I'd say it works for this game. Simply do the following:
- locate mod using Steam Workshop
- Copy URL for that mod
- Go to Steam workshop downloader
- Paste URL from above step into downloader text box
- Wait for the workshop mod to come up
- Press the download button

This does not require a Steam account, whereas you need an account to "subscribe" to a mod if you want to get it via Steam.

I originally used this technique for the Shadowrun Returns series of games. More details here: https://www.gog.com/forum/shadowrun_series/how_to_get_steam_workshop_mods_without_using_steam

Never heard of that tool before. Cool! :)