With apologies to all, this is the nub of my concern. And it may be that I am overthinking this, creating problems where none exist.
/- Are Irish credit card and current account debit card providers allowed to offer their services to Irish now living (and resident) overseas? (I was asked to provide proof of postal address recently)
/- Are Irish banks able to text passcodes to non-Irish telephone numbers? I experience difficulties where I give my irish number to continetnal providers.
/- Am I creating problems where none exist? I thought the new PSD2 played a part in all this.
So - proof of address etc is required when opening an account in order for the bank to show they have done due diligence on their customers. Once you move, you're not required to close the account (my son lives abroad but still has his Irish account). What happens if they need to refresh their KYC... or if you change your address on their records... to an overseas address. That leads to.....
Can Irish banks open current accounts for non-Irish based customers? I didn't think there was any legal reason for them not to. They would still need to hold KYC documents but fundamentally I don't think there is an impediment (remember 10 years ago a lot of people were planning to open accounts in Germany?)
So if there is no reason for them not to have an account with an overseas contact, I can't see why having an overseas phone number would be an issue. There may have been reluctance in the past where messaging to overseas numbers would have had a cost impact but that's not relevant now (within the EU). So it could be that the continental providers you mention are just not used to seeing foreign numbers.
PSD2 is silent on this afaik - I think what you might bump into is banks not used to having non-Irish numbers (or even old systems which can't handle country codes???). They only require it for security purposes so it is in their interest that they have the best number for security purposes