Regarding G5
https://static.garmin.com/pumac/AML-SA01818WI_1710.pdf
https://static.garmin.com/pumac/EASA_10060846_01.pdf
Certification basis is FAR 23
therefore not, at the moment.
One limitation may be the fact that is not possible to adjust zero angle of artificial horizon during the fly,
with non certified G5 that is possible