For power monitoring this looks like the best way to go
I used this as a junction box when I did my security system several months ago, they also make a larger size 17x14:
I installed terminal blocks for 11 alarm zones, 3 fire zones (main floor smoke/heat, main floor monoxide, attic fire/heat), primary power bus, fire power bus, aux bus, siren, and input for ceiling mounted emergency lights. The upper floor keypad wire is also in there, that is CAT6A in 2 sections and connected with a patch cable, that way I had the option of a POE keypad in the future with minimal changes.
it is cramped, in hindsight, I would would want to do 2 of them in the attic, but it was summer and 140 degrees up there, doing 1 of of them including a full custom conduit job and running all the wire was… enough. Working in the middle of the night was an option on some days, and was the only way I could do the wire connections.
An identical and even more cramped box is in the basement next to the security panel, all the wires from the upper box go to terminal blocks in the basement box, and there is a metal box in the garage which also goes to the basement box, that one has 5 alarm zones, and relay control of the garage door openers, plus aux power, and the feed to that box also has garage fire/heat and siren. All of those are run through EMT conduit.
That run was very time consuming, pulling wire myself through metal conduit took a very long time, but the results are awesome and the whole thing is very tamper resistant. The previous owner had a large amount of exposed conduit for power feeds, so it does not look out of place.
I did 18 gauge between the boxes and for the entire garage, then 22 for the individual zones out of the attic box. I used 16 gauge for the main power feed between the boxes, so I had more flexibility for expansion, as a single 8 conductor wire would now give me 5 more zones.
I am using an Envisalink4 with a Honeywell panel, though it is out of the box designed for DSC, they have a list of models, I think PC1864 is the one to go with as it has the most zones available. The EVL4 is native supported in HA. There may be other ways to integrate DSC panels but I am not familiar.
I tried to add a wired deadbolt sensor for my front door, but there is just not enough wood there to install it, after about an inch there is a tall window. Deadbolt sensors are a great idea but kind of need to be installed along with the door, and not as an afterthought, so we only get door sensors and window glassbreak sensors.
The geometry of the door is pretty much set in stone, if the hole is drilled in the correct location in advance, when the trim goes up it is super easy. Doing it in advance means you can have main floor door sensors mounted on the bottom or side of the trim, and that may be the best option based on the design of the house, our main floor is the 2nd floor, so everything up here is an attic drop.