Roast my idea - agency management software with powerups

Hello,
Occasionally I work making Wordpress-based websites. Client sends me email with brief written in Word containing content and idea how website would gonna look like. My task is to organize informations from brief and put it into newly installed Wordpress instance. Sometimes I need to put photos in gallery (which is sometimes hard for non-tech people). Brief in Word is often not well organized. I can't also talk about specific parts of brief.

Here is my idea,
create a tool where developer/creator/agency and client can meet and talk about project. Tool designed specifically to communicate, not plan work inside teams. The main feature would be a document editor, like Notion, where both sides can create briefs and documentations, comment specific blocks (start chat threads based on blocks). Second feature would be invoicing and payments operations.

Current market:
Monday.com - good tool, but for me it is too complicated. Not designed for communication between client and creator.
AgenciFlow.com - very similar tool to my idea, but in my opinion not very well designed. Taking notes could be much better (Notion inspired editor). And it is very expensive - $249 monthly!

What do you think about that project? Would you use it? If yes, at what price?