Stylus and Apple Pencil alternatives are two different things.
The former works on any touch screen, isn't connected to the device via Bluetooth, lack palm rejection and are generally not great for precision. The latter which I recommend work specifically with iPads with Pencil support.
I own a £28 one that I use with my M1 iPad Pro. It has the same shape, tip, feel, palm rejection, magnetic charging and tilt sensetivity as my Apple Pencil 2. The only features messing are pressure sensetivity and double tap to swap between pencil and eraser. Other than that their differences are imperceptible.
That's exactly pressure sensitivity that makes all the difference in the world, and is exactly what the Apple Pencil excels at.
Do you NEED pressure sensitivity? If you are just writing, it's just a nice plus. But if you are DRAWING, it captures all the subtle nuances and warmth handmade drawings usually have. So, while not mandatory, it makes all the difference in the world.
There are a few select styli that do have pressure sensitivity on the iPad. But they're very old, and the few ones I found have half the pressure sensitivity of the Apple Pencil.