What problem does this address?

Currently the only format these blocks can entertain is label + icon. But sometimes a design might dictate the use of just an icon, or just text.

What is your proposed solution?

It would be a nice enhancement if were possible to choose between:

• Text only
• Icon only
• Text + Icon

And in situations where the icon is present, allow the user to select from some preset characters or potentially upload a custom one.

There's a lot of overlap between this and the following:

• Add ability to style and/or use a custom icon for responsive menu  #37930
• Customise Nav block mobile menu toggle text #40580

It would be nice to design a solution that works for all such scenarios.