We are planning to implement Search functionality for our DX customer using Elastic Search. I doubt if we can use the same indexer for both Tridion Sites and Docs.
Any suggestion on this?
No, You can use the same elastic instance to have two different indexes for docs and sites.
OOTB - IQ-Index and IQ-Query services only supported for Docs.
Note: IQ services won’t work with the SI4T index for sites.
I hope it helps.