Power line is no replacement for a decent wired or even 6GHz backhaul

I am confused. Assuming you are in Canada.

Is your “Current Scenario” in a different domicile from where the “Required Scenario” will be?

Is Rogers your current ISP and will still be in the new Townhouse?

If the ISP demark from Rogers is a Coax cable to the XB7 in the garage, simply use a F-type barrel connector to connect the incoming coax from Rogers to the coax cable running to the basement. Then relocate the Rogers supplied XB7 Gateway to the Basement. Then connect your mesh and Ethernet connected devices as norman.

Why do you need a MoCA splitter, when all your equipment lives in the basement? Why even mess with MoCA unless there is some other connectivity that I am missing.

Synology. And do not buy a 2-drive slot model. Go with either four or five drive capacity. You will be wanting to upgrade within the next four to six years.

https://www.synology.com/en-us/support/nas_selector

Then purchase on Amazon.

Utilize the ground connector on all of your IT equipment.

Every Ethernet connection needs --> https://www.amazon.com/dp/B07H5PWWQ1/?coliid=I2PEOQH58OLZRF&colid=27J18KZ6WBXEZ&ref_=lv_ov_lig_dp_it&th=1

No problems, just follow the cable suggestion from “badgerAteMyHomework”.

Start at the top attach a small weight to the cable, https://www.amazon.com/Monoprice-Cat6-Ethernet-Patch-Cable/dp/B01M3VDWKB and let gravity do the work of running it downstairs.

I have used this device multiple times; https://www.amazon.com/gp/product/B08K2MXBPR It works amazingly well.

Ethernet does not negate or negatively impact Mesh. The largest benefit of a Wi-Fi Mesh is one consolidated SSID with automated roaming of mobile devices.

Look at Firewalla. Even their cheap Purple is an excellent router. As long as you will not be messing around with VLANs or VPNs, it will serve you well.

As for the Wi-Fi, go with a TP-Link Deco mesh. As long as you don’t have an need for Wi-Fi6, mainstream acceptance for that or Wi-Fi7 are years out, I would recommend a Deco XE75Pro Mesh.

This is the config that I have and it is amazing! I have well over 75 networked devices. Here is my network; https://imgur.com/a/wysF2WS

As long as you have another open POE port on your switch, use this. https://www.amazon.com/gp/product/B08JS45B89/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

It is a POE Combiner Splitter Adapter to run 2 IP POE Cameras on 1 single cable

Fiber is great, but really overkill for anything other than Enterprise, not necessary for home use.

If you are burying a pipe then I suggest PVC. Use at a minimum 2" Schedule 40 PVC, & set it up with a pull line just in case you want to run additional cables in the future.

I would suggest, unless you are GREAT at terminating Ethernet Cable ends, that you purchase a premade Cat7 Shielded Ethernet cable for use in your PVC. You definitely want a good quality Shielded cable to eliminate any possibility of interference from any other lines that may get pulled in the future. I have used these Ethernet cables in the past and they work extremely well. https://www.amazon.com/Ethernet-Adoreen-Heavy-Duty-Shielded-Waterproof/dp/B09TP7YKST

How to run a “pull string in conduit”; https://www.youtube.com/watch?v=NOG-E8NQipY or https://www.youtube.com/watch?v=Frt0vJ4k15g

Poly Pull Line; https://www.amazon.com/ATERET-PL6500-Poly-Pull-Line/dp/B0B4F8FFT1

I would suggest that you get a TP-Link Deco Mesh. It can be configured in AP(Access Point) mode or in Router mode. So you would connect the first one to the Ethernet coming from the Starlink. Configure your Deco using the APP on your smart phone. Set it up in AP mode. The connect and configure the next Deco node. You can have up to 10 Deco satellite nodes in the mesh.

So once you have all of the Deco mesh nodes configured in AP mode, use the second port on the Main Deco Node to connect to an unmanaged Ethernet switch. From there connect all of your Ethernet lines to the switch.

Now connect the Ethernet cable in your detached workspace to one of the Deco nodes. If you need more than one Ethernet connected device in the detached workspace, just add another switch, either before the Deco in that space or after using the second Ethernet Port.

Now you will have Wi-Fi everywhere using the same SSID and multiple Ethernet connections.

The main thing to make sure is that you either place the Starlink Router into "Bridge Mode and disable the native Wi-Fi. OR Simply ignore the Starlink Wi-Fi and connect nothing to it.

I have had TR-Link Deco Wi-Fi Mesh nodes in my detached, un-heated, garage for many years, with no problems.

I live in N/W Ohio where it occasionally gets down to 0˚F for days on end and in the Summer it can get well over 100˚F.

The Eero 6 has Operating temperature range of; 0˚C- 40˚C / 32˚F - 104˚F. That is the exact same specs as my TP-Link Deco XE75Pro. You should have no problems.

Here’s hoping that the distance and construction allows a good signal and connection to the nearest Eero node.