Unity-SerializeReferenceExtensions VS Markup-Attributes

for serializing interfaces and abstracts, this is phenomenal: https://github.com/mackysoft/Unity-SerializeReferenceExtensions

This one allows you to serialize a reference, like Unity's SerializeReference. However, in the inspector, you get to create an instance of any type the reference can hold. This is extremely powerful for modular systems like card games or weapons.

Unity Serialize Reference Extensions

Unfortunately, attributes can only annotate members or types, not scopes. NaughtyAttributes, as suggested below, is excellent, but I find MarkupAttributes to be even more elegant -- just one attribute is needed for a foldout group, as opposed to the same attribute on every field.

Markup Attributes - Does layout and grouping of fields using attributes. I find it's styling to be the most inline with native Unity, and most likely what I will be in my next project. It also supports material editors. Overall it is quite light weight, and good quality.

Here is the link: https://github.com/gasgiant/MarkupAttributes