If you have an optic cut on your slide, and it is an RMR footprint, you maybe able to use a 01 adapter plate to mount this product. Otherwise, if you do not have an optic cut at all, there are aftermarket adapters out there where you can mount on the rear sight.
Yes if you have a Glock 20 MOS with an RMR optic cut, you will need an adapter plate 05. If you don't have an optic cut, there are some aftermarket adapters you can mount on your rear sight you can use instead.
The ADE Advanced Optics RD3-012 Mini Reflex Green Dot Micro Sight will be compatible with your Glock 17. Your Glock 17 should have included adapter plates for mounting optics. To mount this optic, you will need to use the #1 adapter plate (Docter/Noblex) included with your Glock.
Yes, the ADE Advanced Optics RD3-012 Mini Reflex Green Dot Micro Sight uses the Docter/Noblex optic footprint and would fit your Glock 34 MOS. You would need to use the #1 plate included with your Glock to install the optic.