Not sure if there’s an easy way, but the m3u files are in plaintext and you can make your own copy and pasting the contents of another.

I do know a few evil internet forum posts that explain and go through quite a lot, but a comprehensive list of providers would be hard to find. Lots of paid ones pop up on searches, as ads, paid content or on shill review sites, so it’s difficult to find quality information regarding all of them. There seem to be ones that have thousands of channels that mostly use world tv stations, and niche specific ones though (movies, cartoons, reality tv, etc.). Some paid providers use proprietary software for watching, while others provide .m3u lists of channels that you can open on VLC Player. Some .m3u files only work if you pay for a service and provide credentials or have a specific ip, and some are free. They’re usually called “IPTV lists”.

Here’s a number of free lists grouped by country, language, region, category, etc. It’s where I got the one I linked in my previous comment from.

Here’s a good conversation about services that was later deleted, but you can read most of the comments from that webpage.

Regarding how to configure smartTVs and other devices to watch is a whole other thing. What devices would you like to use it on?

Have you tried IPTV lists?

Open up this free list with VLC player and hit Ctrl+L to open the playlist (the list of channels). They seem to have at least 3: QVC Japan, NHK World Japan and New Japan Pro Wrestling World.

You might find better lists for japanese TV if you dig deeper into IPTV. Note that lots of lists are paid.

Good luck!