Oki, got it. Best if Shosho replies for themselves, but in the past once I made a smilar thing using X/Twitter spaces and Nostr ZapStream but you'd need one extra streaming tool like OBS (dekstop) or Larix (mobile) & a premium/paid twitter account. See here

when you are setting up the upcoming stream on Zapstream you can choose a forwarding option (YT, and some others) or simply pick up 'Custom' to connect with Twitter spaces ; on X through broadcast studio or media studio, sth like this, you build a new streaming source and copy the RTMP url to put into zapstream (attached screenshot: rtmp://) - this should automatically stream on X when you start streaming on Nostr (Zapstream) ; here you simply don't turn on the camera but add some banner in the background. But you use external tool to mange, like OBS (installed on dekstop), I guess Riverside Paid - Live Stream should work in a smilar way where you add the keys and the server url --- see the 2nd & 3rd screenshot.

. Hope this helps. If you want we can run a test together. or maybe Shosho has its own simpler option.
@Avi Burra is also regularly streaming live on Nostr, some maybe will have extra insights to share.