Is It Possible to Arbitrarily Sort Apps in the Portal?

You cannot arbitrarily sort apps in the Portal.

Note that "Created Apps" and "All Apps" are displayed in descending order of creation date in the portal, but in case of "Favorite Apps", most recently registered app is displayed first.
Favorite apps can be set for each user. For details, refer to the following page.
Adding Apps to Favorites
* "Favorite Apps" cannot be bulk configured by an administrator.

You can check favorite apps by selecting "Favorite Apps" from the drop-down list in the app section of the portal.

If you want to allow multiple users to easily access frequently used apps, you can paste such apps in the "Announcement" section of the portal/space, or you can insert URLs of such apps as links.
How to Use Announcement
Attaching Apps to Spaces or Threads