Hi Abilio,
Julio Sillet has some nice textures which would be a nice addition to any texture library (some free some not).
To help with setting up a new material you might want to consider the Rapid Pbr Material Creator $ addon: https://blendermarket.com/products/RapidPBRMaterialCreator
I use the Extreme PBR Evo $ addon which lets you add additional libraries. For example, Julio’s is compatible.
Have you tried the built in Material Library addon? See https://docs.blender.org/manual/en/2.83/addons/materials/material_library.html for more info. I’m not a huge fan of this one but it works.
I’ve heard good things about Asset Wizard addon https://wp.h0bb1t.de/index.php/about-asset-wizard/ but haven’t tried it.
Until asset management is finally integrated into Blender (2.92 apparently maybe) we’ll be dealing with a mishmash of solutions.
Others you might want to investigate:
Simple Asset Manager: https://www.blendernation.com/2018/11/19/add-on-simple-asset-manager/
Asset Management $: https://blendermarket.com/products/asset-management
BAT & BAM are now both outdated I believe. Feel free to correct me if I’m wrong.
Also, the Lazy Asset Browser Lazy Asset Manager is interesting as it uses a file browser type of solution (no thumbnails). Might give it a try one of these days.
Cheers and happy blending.