They now (within the last year or so) sell a replacement dash for the 88-94 GMT400 models, but none for 95+.
You could try strategically placing some butyl tape along the bezel perimeter. It sticks pretty good and may do the job with the rattles. Plus, it’s removable. It’s that tar-type stuff in case you aren’t familiar with it:
Otherwise, I’d look at one of those glue-down dash caps but they’re paint to match and wouldn’t really remedy your attachment issue at the front. But, it could cover up a creatively placed repair.
You can still sometimes find the dashes in the junkyards though the eBay users sell them as well. Be careful, though, as a lot of people break the support bar rivets off of the sides while removing it. There’s a cleaner way without breaking it.
Your bezel clip on the left is what caused that particular dash crack. The dash didn’t enclose the entire hole like the other ones; it was just a backward C-shape so the metal clip pushed down on the bottom part until it gave way at the top. Which yours did. The remedy is to either remove the bezel clip or press it flat so that it doesn’t crack the dash. I added a smidge of the above tape on mine and it holds fine.