Channel invite limits before launch

Your understanding is basically correct:

• Around 5 channels per app
• ~200 users per channel

So yes, maybe you can do like 1000 users total for private channel invites pre-launch.

There’s no "your-own" way to increase channel size or add more channels beyond the limit

But! there's options if you need more testers:

• Use multiple apps/app IDs (common workaround for large tests)
• Move to public distribution when possible
• Contact Meta developer support to request an exception (not guaranteed and honestly I haven't seen that work)

For large-scale testing, most teams don’t rely solely on channels.