fraaram38 - Grenoble-Alpes Métropole Routes Métropolitaines
Nothing on Oct 2020 GSV nor OSM.
OSM + GM do still indicate D numbers, only yellow D numbers on 2023 GSV.
wikisara indicates some "blue metropolis" routes but with D numbering

The route articles indicate that the routes are maintained by the metropolis since 2017.
fraaram69 - Lyon Routes Métropolitaines
Nothing on Oct 2020 GSV nor OSM except of M6 and M7, former A6 and A7.
OSM + GM do still indicate D numbers. There are rarely road numbers anywhere in the field on 2024 GSV. BUT
wikisara indicates this (google-translated):
Since January 1, 2015, it has been entirely located within the territory of the Lyon Metropolis (69M), which ensures its operation while retaining its D1 number.
It seems that the metropolis does just not change the road numbers nor yellow signs except of M6 + M7 (blue signs) that are former A6 + A7 segments. This might be a
GO for drafting the system
Edit: The routes should get the "69M" banner so that we will get D29-69M route names for the metropolis route but retain D29-69 for the departement route.