The insurance is useless. It could take you 6 months for a settlement and then, if something is damaged, they have the right to have it repaired instead of replacing it.
BTW, just to give you a heads up, the post office now has a new class of priority. Regional A and Regional B. These are flat rate with I think a 20# limit per box. The A box is about the size of a toaster. The B box is bigger. The PO gives you the boxes just like regular priority flat rate. You’re charged based on origination and destination points, not for weight.
As an example of how much this can save, I bought 5# of something recently. Vendor was going to ship in a medium priority box for $10.95 or around there. Regional A priority was about $5 TOTAL! BIG difference!
If it were me, I’d file a complaint with the postmaster general. It was very obvious someone cut that package open in transit. That is mail theft and believe it or not, the post office does NOT have a sense of humor in this regard.