Before I bought this game, I should have researched this a bit more, i.e., actually clicking on the links from the search engine instead of just assuming they still exist. I've got a couple dozen hours out of the game, and I'm running out of replayability. Which is fine; I bought it during the Winter Sale and got more than enough playtime to justify the cost.

But, just like with Stardew Valley, once I hit the "end" of the game, mods would probably give it new life. But the official site's mods page no longer exists, the official site's blog entry on modding goes to dead links, Nexus has one outdated mod, and Steam only installs into games you bought on Steam, evidently.

Is there any way of getting at least some of the Steam mods for this game? Or is it just time to uninstall and walk away?

Thanks!

Your only option is to snag the steam version during steam's big sale, I'm pretty much in need of mods and this will be the first time I have to buy a steam version of a GoG purchased game... no, thanks to the devs!

Oh, thanks. Does that mean I have to play it on Steam, too? Or can I just buy it there and copy mods to my GOG games directory?

I never tried that so I would not know, I would think that GoG is incompatible with steam mods via the workshop, you could try it out it couldn't hurt...

Mods from the Steam Workshop are indeed compatible with the GOG version of the game.
If you can download the mod file--either, by subscribing to the item listing in the Workshop, if you own the Steam version, and using the official SteamCMD command-line utility, or by using a third-party site/tool to download Workshop files--then you can place the .sxlmod file into the game's LocalContent/packages directory, and then run the Staxel.ModManager.exe program from the game's bin directory. If the Content Builder doesn't run automatically after accepting the mod installations, then it can be ran manually by selecting Tools > Run Content Builder in the Mod Manager.
If you have the Steam version of the game installed, then subscribing to the mod listing on the Workshop and running the game will automatically run the Mod Manager, extracting the mod files into the game's LocalContent/mods directory. Simply copy and replace this directory with the GOG version's, and you'll successfully have transferred the mods.