Why not a Unifi US-8?

Assuming a quality managed 2.5gbps switch, this topology should be no problem.

(FYI, the terminology “Layer 1” etc has special meaning in networking, might want to choose a different way of denoting your segmentation)

If you are using your ISPs device as your router, they see the MAC (hardware) address of each device on your wired and wireless network and know the make of each.

If you substitute your own router, the MAC isn’t passed through and they’d have a tougher time knowing exactly how many and what kind of devices are in your home network.

Additionally, some routers (and all OpenWRT routers) can run a “full tunnel VPN” client, obfuscating your traffic from your ISP’s deep packet inspection and preventing them from enumerating your internal clients.

Some “cable tester” devices offer a pair-by-pair cable length test, the inexpensive models accomplish this via simple capacitance.