I would use all pulls and skip the knobs, I think a pull is easier to use especially if you plan on aging in place in that home. I’m only using one knob in my entire kitchen. I would prefer to use a pull but since it’s a tall narrow spice pull out I think the knob would look better.

I have double pulls on my larger drawers in my current kitchen and I like the way it looks but have read that unless you use both pulls to open the drawer it causes issues and I almost never open the drawers using both pulls so you may want to skip double pulls.

"I think the premise is to have pulls be *no more than* 1/3 the drawer length."

I think designers invent "rules" like this just to have rules.

I have never paid much attention to such nonsense. There is a limit, of course, to how wide pulls can be. You don't want them to interfere with drawer operation. Other than that, anything that looks good to you is just fine.

As for variations in length, don't worry about it. There is no rule that all pulls have to be the same size, although the same general design is good.

One thing about pantry pulls. You are probably going to be opening pantry doors with arms full of groceries, so a pull you can operate with an elbow, wrist, knee, or one pinky finger is a good choice.

I would use a single pull even on your widest drawers. With modern drawer slides, two pulls are more of a nuisance than a help.

One thing the "rules" don't take into account is that for any given pull design, there are a limited number of available lengths. The ones I used came in 5, 9, and 12 inch (on center, total lengths were 7, 11.5, and 15.5). So it's unlikely that you will even have the option of using "too many pull sizes."

I think 9" would be fine on your 27" and up drawers.

Here is a helpful article covering this topic:

How To Choose The Best Size Pulls For Your Cabinets Drawers

The above was a very helpful article!