okay, I've never seen this suggested anywhere so I assume there's a good reason it's not done, but here's what I think could be a real solution to the problem:

nets.

obviously this could only work for situations where the person doesn't have a gun, but they do have a large bladed weapon or something. Part of the problem is that when the assailant has a knife, it's really risky for any officers to get close to them because they can get lethally stabbed really quickly. And tasers and pepper spray aren't very reliable, and we'd like to avoid using a regular gun, right?

Here's what I'm imagining: they basically have these dense, sticky nets. As soon as they get the net on the person, it sticks to their skin, clothes, and to the net itself, and makes it so they immediately can't move that much. There would be no risk of suffocation because the net is mostly holes. It would be made of a tough enough material that it couldn't be easily cut, especially given their limited mobility.

to get the net on the person, they could have two officers hold either end of a long net and then encircle/clothesline the person from a distance. Once a single net has touched them it should be really easy to get more nets on them. You could do other things too, like maybe a t-shirt cannon that flings the net out from a distance.

so once the person is covered in a few nets, frustrated but mostly unharmed, they could walk up and take the knife away. Then they could use some safe chemical that would dissolve the net's stickiness to free the person. This is kind of like those "man catchers" they use in japan to hold someone immobile from a short distance, but those are still prob too risky and require too much skill for the average cop.