My group and I enjoy having a ton of options when it comes to D&D 5e, be it new (sub)races, new (sub)classes, new feats, or other additional addons/features/variants. It is easy to determine which products WotC officially released. But we don't restrict ourselves to those. We also resort to more "experimental" sources (e.g. Unearthed Arcanas), as long as we know that WotC supports or endorses the product/author.
For example, everybody can put a product on dmsguild, even if it is bad or not (really) in line with the principles of D&D. But there are also some (ten?) special authors, called Guild Adepts, that were announced by WotC. My group and I assume, that the content these people create is therefore “approved” by WotC. It’s not quite an Unearthed Arcana, but similar enough. (Especially, Xanathar’s Lost Notes to Everything Else is really good).
Another example would be the content of Matt Mercer. Although his Blood Hunter Class is not listed under “official” on DnDBeyond, it’s neither listed under “homebrew”. It has it’s own little category called “additional”. So, we decided that Mercer’s stuff is obviously not on par with products officially released by WotC, but similar to the content produced by Guild Adepts.
I’m always looking for more D&D 5e content. So my question is:
Are there any 3rd party products for D&D 5e endorsed by WotC?