You have probably seen @Mike van der Valk replies that there is work happening on the topic of mentioning. We are indeed working on the topic and exploring different possibilities. We have now couple of possible solutions that we could use your feedback on. I am looking for 6-10 participants who are willing to test out our first design prototype (no development yet, only clickable design). 
For this, please use the following   scheduler link to book a time in my calendar for a quick Zoom call. As we are currently looking for a limited number of participants I might close the link as the intended number is reached.

If it happens then please feel free to indicate your interest by writing me an email: liisa.pool@pipedrive.com so that I could include you as the tester in the next round of testing.

Thank you a lot!

Best wishes,
Product Researcher