In Office 365 from the SharePoint admin center it is not possible to quickly see which site collections are PWA site collections. The only way currently to check in the UI is the select a site collection then click the Project Web App button on the Site Collections ribbon and see if the Remove and Settings options are enabled:
If you select a normal SharePoint site collection these two options are disabled:
As you can imagine, if you have many site collections this could be quite a slow process. There is a simple and quick answer to this, PowerShell. Using the SharePoint Online Management Shell you can access the properties of the site collections, details on the SharePoint Online Management Shell can be seen below:
I have used the PowerShell ISE to create and run the script, to use the ISE you will need to firstly install the SharePoint Online Management Shell on your machine then import the module using the command below:
Import-Module Microsoft.Online.SharePoint.PowerShell -DisableNameChecking
Once loaded, a simple PowerShell script can easily identify the PWA site collections:
There is a –Filter parameter for the Get-SPOSite command but it doesn’t allow you to filter on the Template property so I created a simple foreach loop and did the filter there.
Or if you want to see all of the site collections and the templates used to create the sites see the script below:
In both examples just update the site collection admin site URL and the global administrator username for the Connect-SPOService command.
**** There is a caveat to this approach (thanks to Brian Smith for letting me know), if you have a normal SharePoint site then enable PWA on the site after it is created these sites will not show as a PWA site in this script. In that scenario the PWA site is a sub site and the Get-SPOSite only gets the root site collections. I guess you could look at using CSOM / REST to get all sites. ****
If would be good to get this information visible in the view from the SharePoint Admin Center, someone has already suggested this on the Office 365 uservoice, see the link below if you want to vote: