what sights are recommended for the Sig 365 XL.

Holosun 407K/507K

I use Trijicon RMRcc's on my 365s.

I favor enclosed emitter red dots mainly because they do a better job dealing with T-shirt lint in concealed carry for me. I have a Holosun EPS Carry on my P365X. If I didn’t already have it, I’d go with their SCS Carry. I have one of their full-size SCS models on another pistol and really like it.

SIG has a new enclosed emitter option, Romeo X Enclosed Compact, which looks impressive and also a compact non-enclosed emitter version or two.

Trijicon
Holosun
EOTech
Meprolight
Aimpoint
Vortex
Leupold
SIG

All are great RDS'. Decent battery life, durable.
One of the things that I've seen is the weird phenomenon of "It cost more, so it must be better!"
When it comes to Red-dots- not so much.
There's about a $300 - $400 difference in some of the RDS' (that's pistol and rifle) that HAVE night vision capabilities and those that don't.
Do you have now, or are you going to get a set of Night Vision Goggles?
If the answer is "NO", you just saved yourself a few $

Look at the footprint of the different RDS on the Sig 365 XL, look at the style of dots (size, dot vs dot-in-circle, triangle...) and start narrowing down what you like.

Sig’s new Romeo X enclosed optics are excellent in my opinion. There’s a full sized (Pro) and a smaller one that will fit the 365 (Compact).

I run a holosun 507k and it has been great. If I had to replace it I would get a holosun EPS carry MRS. It is the same size but has a closed emitter so you don't have to worry about dust.

If you decide on holosun check the classifieds. We have a member whose pricing can't be beaten.

Look at the footprint of the different RDS on the Sig 365 XL, look at the style of dots (size, dot vs dot-in-circle, triangle...), [justme] not made in Red China[/justme] and start narrowing down what you like.