I've been looking around at https://jspreadsheets.com/ and tried many of them, but still can't put my finger on which one to go with. My requirements are more on the viewing/grouping/searching side rather than editing/formulas etc. but any impressions will help.
FWIW, if you are talking about thousands of rows (or millions), it would be best to paginate, filter, and search on the server, with your grid just being a rendering widget. Doing it that way also makes your grid widget fairly replaceable, so choosing one should not be a blocking decision to starting to code it up.