USPS site while not as easy to navigate as the catalog can be navigated for philatelic purposes. I suggest clicking Shop and in the drop-down menu "Collectors" there it is arranged more for collectors than non-philatelists. Also to the right are various check-off boxes to better navigate. If you want to view only those stamps in coil format, you can check under Format to the left "Coils" and coil stamps will appear.
Another excellent feature of the USPS that I do NOT see at other worldwide postal services sites I have looked at thus far is the Product Specs section under each stamp (below the Description. A comprehensive summary of the stamp's features and printing process. Here is one example for the 2013 Inverted Jenny $2 souvenir sheet that is still on sale - again select Product specs - https://store.usps.com/store/produc...reinfofooter
Another great filter on the USPS site is year of issue. I selected the boxes for 2007, 2008, 2011, 2012, 2013 and 2014. You will see stamps that would be hard to find at local post offices as some of these simply don't sell well (I have been having that problem finding the Saving Endagered Species semiu-postal while the Breast Cancer semi-postal is easy to find.)
Go to this link - https://store.usps.com/store/result...estid=484915
So I agree the site is not entirely user-friendly but with patience you will be surprised what you may find. Generally it matches the catalog. The only items that may not show on the catalog and site are a few issues that are still permitted to be sold at post offices (for example all denominations of the American Crafts low denomination stamps will be available at post offices until Dec 31 and then the 4, 5 and 10 cents ones will not --- only place to get those will be entirely from the secondary market and stamp dealers). The only way to possibly learn of this directly from USPS is to scroll at the bottom and in the small print they have "Newsroom" which actually is an engaging resource with recorded podcasts and all recent announcements. But it is a bit buried in the site. Go to this link for the USPS Newsroom - https://about.usps.com/newsroom/