I'm no expert on this, but a minimum viable size exists and it's much larger than what you could just launch into space. I watched a video on this years ago, I

I'm no expert on this, but a minimum viable size exists and it's much larger than what you could just launch into space. I watched a video on this years ago, I don't recall the exact relation to size but if I'm not remembering this completely wrong there's a minimum size you need for a fusion reactor to "ignite", ITER is huge for a reason.