Well they are all magnetic impellers unless you go with large size pumps like Little Giant or similar.
Any submersible will be the same style impeller/motor as the Aquaclear because that is the safest and most reliable because all the electronics are completely sealed from the water.
I'm rattling it around in my head and I really can't think of a way to design a direct drive submersible pump without it having an inherent leaking/shock risk.
The completely sealed magnetic drive pumps are absolute brainless simplicity, that's why they work so darn good and are reliable as far as the basic design, won't speak to specific manufacturers or models, but the basic concept is relatively flawless for the application it is used for.
Plus with a direct drive pump you introduce far more moving parts and potential failure points.
For the sizes/flow rates needed for small aquaria, that design is perfect because it is also self cooling/lubricating, both issues with direct drive pumps.
I'll wager you could find a small direct drive pump somewhere, but have my doubts that you will find a pre-made factory filter with a direct drive pump unless for large aquariums.
My suggestion is buy something better than an Aquaclear...I never did like that brand.