DL-WRX36 Setup Questions

After some research, I've zeroed in on the Dynalink DL-WRX36 as the base device for a new OpenWrt install.

I've searched the Wiki and the forums and think I have a good handle on the installation procedure and have found videos that describe setting up distinct Wireless SSIDs like:

I'll also likely set up the WRX36 as a Wireguard client based on:

Apart from the wireless and VPN setup, I do need to restrict one wired client from connecting to the other wired clients, wireless, etc. to its own LAN or VLAN (with only access through Wireguard to the Internet) for security purposes.

As best I've been able to gather, I don't think the WRX36 uses the newer DSA or the older swconfig so it is unclear to me how best to setup a VLAN.

I'm wondering what is the best way to segregate a wired client. On the WRX36, would a VLAN be best or would creating a separate LAN with one of the switch ports be better?

If anyone who has a WRX36 could shed some light about what is best along with any step by step setup instructions, would be much appreciated.

Thanks in advance!