No as I can recall. Earlier devices than 1xxx (e.g. some StreetPilots, nuvi 2xx/7xx and related devices) remain stuck with NT or earlier OF (non-NT) mapping use.

There was a case of Honda Goldwing devices (somewhat related to OF-only StreetPilot 26x0 series) getting a firmware upgrade to enable additional use of NTs when earlier version fw only allowed OF maps.

Therefore, if they wanted Garmin could probably issue upgrades for any legacy devices to use later format mapping. Maybe even OF>NT>NTU is possible in theory. They'd never do it though. Not quite intentional obsolescence of course, many older devices wouldn't be physically capable of dealing with the very large size and high compression of modern map image files regardless.

Other fw upgrades were done for nuvi 2xx/7xx and related series to increase the usable map .IMG size limit from 2 GiB to 4 GiB, the former being the previous FAT size limit and the latter the FAT32 limit. They can likely do something similar to allow use of exFAT or even NTFS format if they wanted to do, which they don't. Although loosely based on the UNIX/Linux types of operating systems, i guess as much as Windows is based but in quite different ways, Garmin proprietary OS is quite opaque even to skilled hackers or maybe they're just not interested enough to bother with meddling with it, unlike the somewhat hackable Win OSs. Garmin's OS is quite the polar opposite of the "please-hack-me" Open-Source Linux versions.