Structured Text span-level custom objects

Happy new year!

I really like that we can customize Structured Text with custom marks. Along with blocks the component is very fully-featured, but one thing missing appears to be: span-level custom objects.

Currently we can insert blocks as paragraph-level items, but there are times where we want to insert custom objects directly into a paragraph at the span level. For example: custom icons, linked popovers, or in our specific case, math formulae.

I understand it’s harder to render a complex inline item than a block level one. Perhaps you could allow for certain blocks to be span-level and represented by an inline link/button that opens a modal where you can edit the attributes?