While I appreciate some concerns raised lets please keep this on topic vs unnecessary rabbit trails. The topic is getting first hand feedback from those who have used a surface unit especially battery powered ones. Their pros and cons. Ones that work well and ones that dont and why.
You are posting on an international *public* forum, this is not a private conversation. As such, lots of people seeking for similar questions- like me, for example- can and will stumble upon this thread.
Some (actually many) of the answers that you consistently do not want to hear about, perhaps are useless for you, but for sure they will be beneficial for those who read it in the future.
Many of those seeking advice on surface units are not scuba certified, do not understand the meaning of breathing compressed air, the efrect of pressure gradient in shallow waters ("It is shallow, what's the worst that can happen?"), nor have they ever felt hypercapnea due to stressed breathing underwater, got entangled with regular scuba- which is bad enough, but much worse with a hookah long cable and flowing water, river, diving with zero visibility, cold water, the remote location and perhaps complicated rescue if something goes wrong. In other words: there are lots of risks in what you are asking and people are stating them. To you, and for whoever else will read this in the future.
All these warnings are for them, even if you find them unnecessary rabbit trails. Superman also does not need advice on the risks of working on repairing an antenna on the roof of a skyscraper building, but other humans probably do.