I found Spotlight's integration with Drive hit and miss, and Gmail didn't work at all for me because I don't use the macOS Mail client. I also have multiple accounts (work, personal) and couldn't find a way to search across all of them. There are also other services which folks on this list and others have asked for (Teams keeps coming up for example) which lack any integration.
Reminds me a bit of how I heard people using Alfred back in the day. I personally use Canary Mail, and have always just cycled through native mac apps that weren't first-party. Before Canary there was Sparrow and Spark briefly. It's not as greta as I'd like it to be to actually pay for, but pretty sure the spotlight indexing works fine enough. It's good to see some push in this area though, anything to make your platform more useful.