

The dedicated Roku replacement remotes from Five Below might work.
AliExpress probably has millions of listings for them.
If you find a smashed up Roku branded TV on the side of road and it has the remote nearby, I’d snatch it. Good chance the remote works for your set.

I believe they tried that (or something similar) at my school.
Didn’t work. Was logistically annoying. Failed after a week or something.