Because every Lightning wallet is a hot wallet. Coldcard Q holds the private keys offline, and is therefore a cold wallet. https://youtu.be/5n14AlwpiEI

Ah, now I get what you’re asking for. The reason that you can’t buy hardware from nostr:npub12ctjk5lhxp6sks8x83gpk9sx3hvk5fz70uz4ze6uplkfs9lwjmsq2rc5ky over Lightning is because nostr:npub1az9xj85cmxv8e9j9y80lvqp97crsqdu2fpu3srwthd99qfu9qsgstam8y8 and nostr:npub1th5mv25h0gc00hggh5wg04ck587sd4n6...