fbx works, I will test it here
ok, I bought the pack and tried to import the .fbx directly into Godot and only the mesh, without materials is recognized.
I dont have much experience with all the material pngs of each model, but I searched the internet and could import in Blender (that also don't recognize the materials by default) and then, inside blender, using the shader editor with the "node wrangler" plugin I was able to point to the pngs and recreate the material, after that exporting as glb (glTF 2.0) gave me the best compatibility with Godot. (details here: https://blender.stackexchange.com/questions/270868/applying-texture-to-a-fbx-fil... )
Not too bad, just looks like exagerated filtered normal maps. I assume you can tweak those in Godot?
So, in your opinion, would it be worth it for me togo and convert all my packs to be Godot compatible one by one and sell them on Godot focused marketplaces?
Im not sure how big the userbase is?
I would probably code a tool that does most of the work for me.
I don't know. I can't tell you how big the user base is or if there is a market for assets in Godot's integrated asset library, I am a total n00b, in the area :)
I can offer you my personal experience only. As a beginner, I chose the Godot route because it's open source and I support free-as-in-freedom software by principle. The same is true for Blender, another excelent piece of free-software, very mature project, getting asset packs to open seamless in blender would be already a great step, a common ground for people on free pipelines.
I don't use Godot's integrated AssetLibrary much and my place to browse free/cheap assets is here at itch.io. Maybe if there is a simple "one-extra-format" export option to include glTF on your existing assets, updating the itch downloads wouldn't hurt. But doing it for the money my guess is that the user-base might yet be too small to be worth it.
Maybe for new projects the overhead is small enough that adding glTF and targeting Godot might be a nice extra selling point. Judging by the amount of documentation and youtube tutorials, I think the engine is finding it's place among the industry (for example, I heard Battlefield 6 stage editor for end users will be Godot-based, but don't quote me on that ;))