First step would be to contact Samsung and ask for the Linux kernel and other open source code for your TV. Without it you won't be able to replace the original OS properly. Also mention to them that they have to allow you to update Linux on the TV or they have to stop using Linux on their TVs.
https://sfconservancy.org/blog/2021/mar/25/install-gplv2/
And they will provide it as required per law. Note that the law does not require them to provide that in a form that would be usable for anything practical without doing moderate to heavy amount of reverse engineering (e.g. here's the source, here's the toolchain that was released in approximately same period of time, go figure out if this can even be built without recreating part of their internal build system, missing configs, etc).
See the blog post, the GPLv2 goes further than what you suggest.
So if my Toyota head unit has FOSS they can provide that source code to me if I ask?