We're currently working on building out our Estimation system in Retool.
I'm quite excited, it's a beautiful piece of software.
Only issue- live commenting and collaboration which we've had in Google Docs and Sheets till now.
- commenting on specific cells in a table to update values,
- Comment on specific text to change things
- Comment on specific components containing values.
For example- "@person please update the sales Tax to 8%"
I have a live editor working in one of my apps. Not quite what you are looking for on a per cell basis, but it might be a blunt tool to fill the need.