A while back I bought an Eotech EXPS3-3 with their G45 5x magnifier. The view is amazing out of  it. I have woken to the glory of magnified sight but at the same time I love those holographic/red dots.

Was wondering, could that magnifier be used with regular red dots?

I have some Primary Arms red dots on rifles. Seems to work when I clipped it on.

I love the g45 behind the aimpoint t2 or any eotech.
Havnt tried it with any other aimpoints but I have some cheaper red dots like sig romeo 5 and primary arms red dots and it works fine but those cheaper red dots do have some extra bloom/distortion when magnified.
Ymmv if you have astigmatism or wear glasses.

Yes

threw an extra G33 on my mk18"ish" build with a T2 on it. seems to work just fine if you get your eye suuuper close to the magnifier to alleviate the minor scope shadow from the offset

magnifiers are magnifiers.  All they do is magnify whatever is placed in front of them.  Any red dot, holo, or reflex sight will work with any magnifier.  They are not brand specific in the least bit.  The only thing to take into consideration is that you will always have better results pairing good glass with good glass.  You may have less optimal results pairing a good sight with a cheap magnifier or vise versa.