This cannot be done. Each TV will need it's own Roku device. So purchase a Roku Ultra or Stick for your second TV. Each Roku would be independent from each other. Not sure why you think they would be linked. Each Roku would be linked under your Roku account.
The short answer is that for independent control, each TV requires its own Roku device attached to it via HDMI.
There is no need for a TV to be smart or have inherent wi-fi capability. By attaching a Roku device to your TV, you are basically giving it a Smart OS (the Roku smart OS). The wifi signal is received by the Roku device itself.
When you link Roku devices, you are basically assigning them all to the same account (same email address), so you can easily just have the same setup on all your devices. (If you add or remove a channel to one device, you will be removing that same channel/app to all your linked devices). Additionally, any subscriptions purchased through Roku directly will be made available to all linked devices.
In order to link Roku devices, just make sure to use the same email address you did with your previous Roku devices during setup. You can see your account/email address from Settings/System/About on the Roku device. You can manage your Roku account further at https://www.roku.com/ and then sign in to your Account Dashboard. (look for the little head icon in upper right of website).
"In my mind I would have a 2nd ROKU connected via HDMI to the 2nd TV that links to my current ROKU via wireless."
The Roku devices don't communicate with each other over wifi- they are associated with your Roku account. (Not a master/slave setup). The Roku device connects to your TV via HDMI and is unaware if another Roku device is in the house. All managed by the Roku account. (email address).
All the Roku devices are capable of wireless (wifi) connection, so budget and preference should perhaps guide you for your 2nd Roku device on the other TV. I personally prefer the streaming players (Express 4k/4k+) over the Streaming Sticks (4k/4k+), but all should give you good results. You can even use another Ultra and connect it through wifi if you want. I would just avoid the older HD Roku Express (the non-4k models), as it really is the basic starter streamer and think the newer devices may give you a better experience for a little more money.
Hope that helps you a little bit.
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102