Buy data transmission for an obscure currency, use obscure lightning software to use the obscure currency to pay a company to transmit data to something you need to buy dedicated hardware for. Hapless optimism aside it’s hard to see what benign purpose this could possibly be used for.

It’s sort of strange to bother with anything custom. Bitcoin signatures have a free, encrypted data channel within ECDSA signatures. You can just broadcast those through the normal bitcoin network without paying Blockstream.

The antennas required are the ubiquitous commercial satellite TV kind which you can probably find on craigslist for free. The other hardware costs < $100. The software is all free (along with the broadcast itself).

"the ability to receive the broadcasts is left as an exercise to the user"