I'm attending an event at the Hilton while staying at the Hyatt. Is it possible to walk indoors from one hotel to the other through the convention center?

I asked the concierge that same question and they said it was possible but a bit of a walk. I never tried it myself but the concierge should be able to provide you directions.

Yes you can, theres an walkway that takes you there

It would feel like miles to walk it, trust me I have tried

Yes

It is not possible to do entirely indoors. I had the same situation, and there are covered walkways from each of the hotels to the convention center which you can cut through (though it does lock depending on the time of day), but they are outdoors. I made the walk 3 or 4 times and it averaged ~15 minutes.