this would need some tests with automation - in case you have the time and want to learn it could be a great opportunity.
There was something similar from Community a user has built:
Apparently, you would need to adapt good parts so, for example, the action is to put the mentioned user to Watcher/Request Participants and so on.
Hello Community! Quick disclaimer: We are running a contest on Community (The Atlympics!) from July 23rd - August 8th of 2021. If you are interested in participating in this contest (prizes! ...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events