View user's availability status in Planner

We want to quickly see in planner if user is now busy or available.

Use case is the following. For today work for some users is planned, some have meetings, some work on unplanned tasks. If this minute some new request comes - we want to quickly see in the plan page whom to assign it to.

We want to see that the user is "now busy" in the following situations (one of many):

Doesn't have planned time for current time, for example if time was planned for user for today from 9:00 to 11:00 and now is 12:00 and no other work is planned yet.
Tracking timer is in progress for this user (he manually started the tracker for some issue)
User manually set status "busy". Applicable when user is on call, meeting etc.

Otherwise we can see that user's status is "free now".

User should have the ability to inform the team that he is busy now with manually setting busy status somewhere, even there is no work planned for him and there is no running timer. Team lead also should have the ability to filter users that are now available.

It may look like in attachment.
Thanks.