If any manga reader app supports casting...
You can sideload Tachiyomi. It will work but using the remote to navigate it is a hassle and you're better off using a mouse for it.
I will use Appvn as google play alternative on my mobile, this is such a big and great app store
One way to do this is install any web browser from Google TV Play Store(Eg: Puffin Tv Browser) and open this website which offers All anime manga for free - https://mangareader.tv/
you can select and scroll to the title you want and read through it !! Bookmark the same.
You can check out mangamew.co, not a bad option
TvBro app wou give you a usable browser if you just read from a website. A mouse and keyboard connected through a USB OTG adapter or a USB C hub would give you a better user experience.
If you read/watch through a specific app, you would probably be able to side load it if you can find a compatible version.