Which hotel are you coming from?
You can't walk all the way to the parks via Disneyland Drive. They have blocked off the sidewalk entry point to cast members only.
You have to get yourself to Magic Way, then to Downtown Drive (the entrance to the Stitch cast member parking lot). You can do that via Walnut or Ball. Follow the sidewalk at Downtown Drive up towards the Disneyland Hotel to the security checkpoint at Downtown Disney. The entrance is just beyond the Sorcerer Hat that marks the entrance to DLH.
There was a rumor that the main security checkpoint (outside the former ESPN zone) was going to reopen when the trams returned, but not sure that is happening. When that opens, it SLIGHTLY shortens the walk. By like 2 minutes.
I would say at a brisk pace, the walk will take 20 minutes. Its comparable to walking from the furthest reaches of the M&F parking structure, which I have done numerous times.