I am taking in an entity as an input, and then using the entity as a trigger. To make the input optional I set default: ''. The problem with this approach is the blueprint will not save, as the trigger isn't valid.
I can't seem to think of a way around this. Here's the repo for the BP. The input I'd like to make optional is 'entity_light'
https://github.com/jay-kub/inovelli-matter-switch-tap-sequences/blob/dev/inovelli-matter-switch-tap-sequences.yaml