I purchased a Roku Express in 2019. I wanted to add some new themes...I read that this can be done by going to the Roku Channel Store; which I did. I was reading how "dozens of new themes are available and the examples of those themes...some free, some paid. However I ONLY see the themes that are already preloaded on my Roku express and there are not "dozens"! And not any of the ones or type that I have read about. Just your basic boring ones! Wasn't sure if I am reading outdated information...if Roku has changed this and only newer models will be able to access such features or why I can't find such mentioned themes.
I don't think you find themes in the Channel Store. If I recall you can browse for themes under the themes menu. Yep, just checked my Roku TV beside me, and there's themes, wallpaper and screensavers available there, some free and some cost.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.