This part is terrifying: does Ireland not have the equivalent of HSR (UK, in combination with a patchwork of other legislation) or HIPAA?
I think you might also be surprised by the level of WhatsApp use in the NHS. It's far more common in actual use than Pando or Teams.
In 2021, when nearly the entire HSE IT system went down due to a cyberattack (including HSE email), literally the entire service ran on WhatsApp and taxis filled with paper records driving around.
What do you mean? I live in Ireland and no health professional has ever contacted me via WhatsApp.
You just get added to the relevant groups by your manager (obviously there's also unofficial social groups) and that's where you'll get 90%+ of rosters, clinical updates, service bulletins, etc.
Missing out on conversations from my extended family, friends (only about 1/4 use Signal and all groups are on WhatsApp), work (the Health Service in Ireland literally runs on WhatsApp), voluntary undertakings (all of which are organised on WhatsApp), organising stuff for the kids (again all on WhatsApp).
So it's a valid fear based on the reality in my social circle and country. Unilaterally moving to Signal means self-imposed isolation.