Currently there is no easy way to create a blueprint function which accepts any type as a parameter. Some engine types such as TArray have this implemented specifically in the blueprint node system using "Wildcard"s. This is the second time I’ve come across the problem of wanting to create a templated/generic class or function but am unable to expose it for use in blueprints.
I also found this post from 2014 stating how implementing better support for this was a development goal. Additionally, a tutorial on creating a UFUNCTION which accepts most structs which states how many of these deep features are currently undocumented.
In almost all cases, having to work around this restriction is messy and time consuming to nail down. It would be a massive improvement to the robustness of blueprints if some support is added to allow for UCLASS/UPROPERTY/UFUNCTION to support either templates or our own wildcard parameters.