Since the client device (any connected wireless device) has to be WPA3 compatible, you will most likely find that you need to change your TP-Link settings to reflect WPA3/WPA2-MIX for your Roku device (and maybe other devices on your network) to authenticate on your network.
Keeping it simple...because WPA3 requires SAE encryption rather than AES encryption of WPA2 (a pre-shared key), my default feeling is that Roku devices are probably not going to connect to WPA3 only setups.
Other than that, there is no reason you cannot setup your router to use your Roku Ultra. If you find that the Ultra does connect with set to WPA3-only, feel free to update this post as would be interested to know results.
Of course, you can always use ethernet with your Ultra and the WPA3 issue would be moot since only affects wirelessly connected devices (wifi).
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