Yes you’re right, Jellyfin isn’t on many platforms but I’m pretty sure they have an app for LG and Roku (Clients here). Although the LG app isn’t the best from what I remember. What I usually do is use an Amazon fire stick with Tailscale for my family and it’s been working well. But also as popularity increases others will be able to contribute more and the apps will become better.
You should try out Infuse. It’s $10/year and I’ve been loving it. Better than any other app I’ve tried and at under $1 a month worth it for me.