Status:
Not at this time.
Portal to check available MSIX applications from software vendors
It would be really great if there were a portal within Microsoft to check for applications from known software vendors that are already available in MSIX format.
Do you mean apps that are available for sideloading and not present in the store?
What is the end purpose of the portal? If you want to see if the vendor of apps (I assume) you want to deploy in the enterprise has an MSIX available, can't you check that directly?
Do you want to see how many of the apps from your enterprise are are already packaged as MSIX or....?