insist if Meghan gave up being a royal they'd zip their mouths permanently will actually stand by their promises?
She's not giving up being a royal. They're giving up being 'senior royals' which is basically saying they don't want to be royals as a full time job and they don't want their roles to be defined by any other palace influence (including the Queen) and want to be free to cash in on their royal profiles. They're not giving up public funding or security, or their platforms and or patronages or their own pet projects. The statement also seems to hint they will be continuing to engage with the woke brand of politics they're both very keen on.
Basically before they would have been expected to do certain things as senior royals, trooping of the colour, Remembrance Day, Ascot, state occasions including banquets and receptions for foreign dignitaries plus overseas royal tours and a full diary of engagements.
Rather than stopping being royal what they seem to want to do is treat royalty like a tap they can turn on and off at will. So 6 months in America writing lifestyle blogs, pushing products and interviews with Oprah pontificating on woke causes , then back for a fortnight to stick on a tiara and some royal jewels and mug for a few photos next to HM so nobody forgets they're royals.
If they were genuinely giving up being royal - fine. But they're just giving up the bits they don't like and hanging on to the perks and privileges.