Yes, this DIY approach is very alpha!
The DIY TX and RX stopped working shortly after the video. It is finicky and seems to have periodic problems with binding for no obvious reason. More bench testing needed.
The DIY RX used with a Hobbyking TX module is much more rugged and I would be prepared to test it in a submarine if the Covid virus would let us return to the pond at Barrow.
The main thing is that your work and observations on the use of openLRS on 400 to 500Mhz enabled worldwide model submariners to have more options for r/c equipment.
Mind you, in the UK, I am a bit worried that the 458 Mhz band could be sold-on. John Robinson tells me that it's main use is control of traffic lights which is preventing it being sold-off!