Green dot sights like the Holosun HE508T-GR-X2 Green Dot Sight generally cost more because they are brighter and stronger than red dot sights. The green dot sight is generally brighter can be seen better in daylight compared to red dots.
You will need on the the optics that share the same footprint as the Romeo1 Pro
Red dot sights that share this footprint:
Shield RMS
Shield RMSc
Shield RMSw
Shield SMS
Sig Sauer Romeo Zero
Leupold Delta Point Pro
JP Enterprises JPoint
ADE Advanced Optics RD3-018 Spike
ADE Advanced Optics RD3-021 Nuwa
Swampfox Sentinel 1×16
Vector Optics Frenzy-S 1x17x24 MIC
Yes, you would need some sort of adapter plate as the P320 AXG has a Delta Point PRO slide cut while the 508T uses the Trijicon RMR mounting pattern mounts.
Yes, you will want to use the RMR mounting plate included with your MOS handgun.
Because the P320 XTEN uses a dual-cut slide for RMR and Deltapoint Pro pattern optics, the Holosun HE508T-GR-X2 1x 2 MOA Dot Green Dot Sight will be compatible as it uses the RMR footprint. However, it will require the use of a sealing plate, like the one linked below:
https://www.opticsplanet.com/trijicon-rmr-mount-sealing-plate.html
The Holosun HE508T-GR-X2 1x 2 MOA Dot Green Dot Sight uses the Trijicon RMR footprint and will not be compatible with the X5 Legion. The X5 Legion is optics cut for optics that use the DPP footprint such as the Sig Romeo 1 Pro, Leupold Deltapoint Pro, Eotech EFLX, and Holosun EPS.
No, the Holosun HE508T-GR-X2 1x 2 MOA Dot Green Dot Sight uses the full size Trijicon RMR footprint, which does not match the screw hole pattern of the RMSc footprint. You will be able to use any optic with the RMSc or K footprint such as the Vortex Defender, Shield RMSc, Sig Romeo Zero, Holosun 407K/507K and more.
Yes, to mount this Holosun HE508T-GR-X2 Green Dot Sight to your PDP, you must request an RMR pattern adapter plate from Walther directly via their optic plate request form (linked below). Once you receive the plate, you can install it to your slide and then install the optic to the plate.
https://waltherarms.com/choose-your-cut
The Holosun HE508T-GR-X2 1x 2 MOA Dot Green Dot Sights use the RMR footprint. You will need the Canik Optics Mount compatible with the RMR footprint and the Canik TP9 Elite Combat. The plate at the link below should work.
https://www.opticsplanet.com/canik-optic-interface-2.html
The Holosun HE508T-GR-X2 1x 2 MOA Dot Green Dot Sights will fit a PSA Dagger Compact model that has a optics ready slide to fit the RMR footprint.