Can NH-D15 G2 LBC and HBC coolers be used on all platforms and do they include mounting hardware for all sockets?

Yes, while LBC and HBC coolers are optimised for the best possible contact quality on particular platforms, they include mounting hardware for all the specified platforms (AMD AM5 and AM4 as well as Intel LGA1851, 1700, 1200 and 115x).

Therefore, while they will only achieve optimal contact quality and performance on the platforms they have been optimised for, they can still be used on other platforms with slight losses in cooling efficiency. In the case of the HBC version on AM5, these losses can be minimised by using the included offset mounting. For further information and thermal performance comparisons, please refer to this article.