All the phones in the OP afaik, assuming 'worldwide' = Tmobile/AT&T in the US. Unlocked Sammy S7/8, LG G6, MotoG5+ [all @Best Buy] and the Pixel.
IDK why their insurance would cover a phone you bought elsewhere.
Worldwide means it supports 4G LTE with bands outside the US when traveling as Verizon phones such as even the LG G4 which is 4G LTE would only work as 3G outside the U.S. due to it not having support of the bands. If you look at a Apple iPhone like the A1661 iPhone 7Plus which is the sim unlocked carrier free model and even sold as the Verizon model, it supports the following:
FDD-LTE bands 1 (2100 MHz), 2 (1900 MHz), 3 (1800 MHz), 4 (AWS), 5 (850 MHz), 7 (2600 MHz), 8 (900 MHz), 12 (700 a MHz), 13 (700c MHz), 17 (700b MHz), 18 (800 MHz), 19 (800 MHz), 20 (800 DD), 25 (1900 MHz), 26 (800 MHz), 27 (800 SMR), 28 (700 APT MHz), 29 (700 de MHz), 30 (2300 WCS)
TD-LTE bands 38 (TD 2600 MHz), 39 (TD 1900 MHz), 40 (TD 2300 MHz), 41 (TD 2500 MHz)
TD-SCDMA 1900 (F), 2000 (A)
CDMA EV-DO Rev. A (800, 1700/2100, 1900, 2100 MHz)
GSM/EDGE (850, 900, 1800, 1900 MHz)
UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
The Essential phone which is made by the guy who headed Google's Android before as seen here:
»
www.essential.com/
as a example is probably the closest one will get as far as bands go:
Network / Bands
UMTS/HSPA+: 1, 2, 4, 5 6, 8
GSM: 850, 900, 1800, 1900 MHz
CDMA EV-DO Rev. A: 0, 1, 10
FDD-LTE: 1, 2, 3, 4, 5, 7, 8, 11, 12, 13, 17, 20, 21, 25, 26, 28, 29, 30, 66
TDD-LTE: 38, 39, 40, 41, 42, 43
TD-SCDMA: 34, 39
It has FDD-LTE 11, 21 that the iPhone lacks but not FDD-LTE 18, 19, 27 that the iPhone has.
It has TD-LTE 42, 43 which the iPhone lacks.
It has 800 UMTS/HSPA+/DC-HSDPA which the iPhone lacks.
Now compare that to what the Samsung S8 Unlocked model supports:
B1(2100), B2(1900), B3(1800), B4(AWS), B5(850), B7(2600), B8(900), B12(700), B13(700), B17(700), B18(800), B19(800), B20(800), B25(1900), B26(800), B28(700), B29(700), B30(2300), B66(AWS-3)
which means it's missing FDD-LTE 27
It doesn't mention anything about TD-LTE/TD-SCDMA support either
It would actually be harder to go looking at different make/models to list the bands compared to listing the bands and generate a list of the devices that have support for those bands since it seems like the companies that make multiple models of the same device for different carriers usually will have the T-Mobile and AT&T models which will work worldwide with 4G LTE because they lack the support for CDMA but the devices made for the CDMA carriers will generally lose the 4G LTE outside the US because the CDMA support would be taking it's place.
Their insurance covers phones bought from Best Buy and even Radio Shack as long as it's a Verizon branded device but if you already had insurance on your account that you are paying for monthly, they should need to cover it since otherwise they should not have charged for the insurance as they can easily check if the device is a Verizon device or not to continue billing for the insurance. It would be different if you activated the device and then try to get insurance since they would then not sell you the insurance.