Summarising state in another table?

Here is the dataset I have used.

While connecting to PowerBI, relationship was created between Site & User and Application & User tables.

Now I created a new column in Application table with name "Status" with following formula

Status = IF('Application Status'[Readiness]=TRUE(),0,1)

Next I added a new measure in Site table with name "SiteStatus" with following formula.

Site Status = CALCULATE(SUM('Application Status'[Status]),GROUPBY(Site,Site[Site]))

Next I added a new measure in site table with name "Completion Date" having following formula

Completion Date = CALCULATE(MAX('Application Status'[ETA]),GROUPBY(site,Site[Site]))

Now we are ready to use these measure to display your required information on report. Select Table visual and select Site to be displayed on it. Apply filter on Site Status = 0. This will display sites which are with completed status. Refer to below image.

Now place another Table visual and select site along with Completion date. Add site status to filter and apply stuatus greater than 0. Please refer to below image.

Hope this will help you to achive what you want.