If both earths/ grounds are bolted to a known good chassis connection, then there will not be an issue.I installed a remote start system and connected its ground wire to an existing interior ground (might be the infotainment system?).
Is it okay to ground two things to the same bolt?
Concur, it's a good ground. Sharing ground wires would be different, as one system can interact with another.
The only pitfall would be a ground loop.
No- ground loop occurs from multiple grounding points- this is a single pointThe only pitfall would be a ground loop