Widget Visibility: add existing block visibility options to the block editor / site editor

[jeherve]

Discussed in #29170

^{Originally posted by tnchuntic February 27, 2023}

Just wanted to ask if there is a plan for conversion of Widget Visibility to Block Visibility? This would be very helpful and useful to have.

I am sure that this will solve a lot of things in the FSE world moving forward.

We currently only offer block visibility options for blocks inside the block-based widget editor. We purposefully restricted those options to the widget editor when we first implemented the block visibility feature (see #17413).

Since widgets are becoming less and less relevant with the advent of block themes and the site editor, it would be nice to bring those block visibility controls to the site editor and block editor.

While the site editor and its templates allow you some control over the different blocks displayed on a specific page, block visibility options would bring an additional level of flexibility and control.