I have run some model(s) of Roku Express through an HDMI to component converter. It works fine but there are some caveats. The converter and the component cables going from it to the TV are larger than the Roku Express. It has no power switch, and has some user reviews that said it worked for weeks or months, so I unplug it a lot. Mine still works, but I only connect it for specific situations, so it only gets around 40 hours of use in a year.
The converter cost about $40 on Amazon. You can probably find a used 40" TV for that. And if your 19" TV is sitting on a stand on bedroom furniture, a 40" TV on the wall will actually take up less space and "disappear" more when it is off, than a freestanding 19" TV will. I just hung a 40" Samsung from 2017 on the wall with a $19 mount. It was easy because it only weighs 15lbs and the mount is rated for 100lbs.
By the way, the Amazon rating on the $19 mount is 4.7 stars. The rating on the $40 converter is 4.3 stars. 4.3 stars is at a level where I am hesitant to provide a link and tell you I'm sure it will work for you.