Tag or Subject for each quote / invoice

Would it possible to have a single text field or tag area for each quote / invoice?

I have a lot of projects for the same customer and mostly write quotes / invoices at the beginnen / end of each month. Most of my time is used to find the right quote to convert to a accepted project and convert that to a invoice.

would be awesome to have a small text next to the quote number to indicate the “use” of the quote, like a subject line

You may simply use a custom field for that.

How would I set this up to show in Dashboard or quote overview?

There was a thread about ucstom fields in the invoice overview some days ago:

Maybe this helps you. I cannot assist with any development as I have much other things to do at the moment.