LODs Go is a simple but very handy tool for LODs checking for Unreal/Unity. For example, if you loaded an fbx file with objects like Object_LOD0, Object_LOD1, Object_LOD2, Object_LOD3 then you can easily try them inside of Blender and fix any bugs and issues according to LODs.
Hotkeys:
0 - Change LODs according to Camera distance
1-9 - Change LODs by a number.
Hi. Do you plan to also offer a Black Friday discount on Gumroad? I only notice one on BlenderMarket.
Also, a tutorial video would be useful for your future customers.