A new item at Skandix for 740, 760, 940, 960 tailgate trim repair.
Maybe it's available at USA outlets?

https://www.skandix.de/en/news/repair-kit-tailgate-trim-volvo-850-v70-700-900/2102/

700/900/V70 tailgate repair kit p/n 9451866 is currently showing as NLA from Volvo, but ipd is still listing as has having stock. There was a similar/identical kit under the MTC brand name. You may occasionally find stock on eBay. The kit does not repair tabs that are completely broken off at the base, just those where the end broke off as is the normal case. If you’re desperate it’s not that hard to fashion your own clips like the Volvo ones or use blobs of black butyl ribbon caulk if only a few are broken and you want to prevent rattling. It was a really bad design that Volvo should have dealt with early on in production. I’ve had the panels off a number of times without breaking them as I knew of the problem. When I had to take one of my wagons in to a glass shop (lawn mower flung a rock and shattered the glass) I spent some time explaining the problem and to be extra careful the panel was pushed firmly back in, but guess what they broke, argggh!
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now