No Harris (legacy brands..) radio will operate on a Motorola network that is NOT P25 compliant. No SmartZone, no Smartnet, no Privacy Plus. (Not that many of those systems are even still operational.)
P25 trunking marked the first time you might find a Harris radio on a Motorola trunked system, or a Motorola radio on a Harris trunked system.
Admittedly, I am a bit fuzzy on the compatibility of later Motorola 9600 baud trunking systems that were "Astro 25" but not fully P25 compliant. Those systems evolved toward P25 standards even as the p25 standards themselves evolved. There may be special use cases where you could get limited interoperability between those two brands, without being fully P25 compliant. Not certain about that.
For quite some time, M/A-Com...Harris...wanted no part of Project 25, as they did not want to sign on to Motorola's pet project, but eventually market forces required them to do so. (Primarily federal contracts, I'm sure.)