I know it's supposedly planned for future MC updates, but it'd be great to have something working sooner. The block would output a pulse when a block updates near it (within x radius, or adjacent to a specific face, etc).

I know Extra Utilities has this as well as an advanced BUD as one of their blocks in 1.7.10. Have you checked to see if it already exists in 1.10.2? I only mention this because Extra Utilities is a sudo default mod that has been in the majority of mod packs since 1.6.4

Added to Vanilla