Solid state electrical gyros (both AI & DI) with battery back up will soon be available from major American manufactures fully certified.
I have seen a leaflet on a Sandel solid state gyro which is claimed to replace (mounting wise and connections wise) the very common Bendix/King mechanical one. No idea if it is certified.
There are various issues in this department because for example if I fit the Aspen unit, I still need the B/King mech gyro for the KFC225 - or something like that. Very few if any avionics people genuinely understand this stuff, and while I have collected a vast quantity of installation manuals, I don't have to patience to read through them unless I need to know
Also the manuals for new equipment are tightly distributed. It's very possible to get into a "certification blind alley" from which the only way out is a load of £££.