No they couldn't they are historic palaces which belong to the nation, even President Macron lives in the Elysee Palace with the French state owning most of the other French Palaces in Paris.
As for food banks go to republics like Brazil or India or even parts of the USA if you really want to see poverty. The average constitutional monarchy like ours or Sweden's has far less poverty than the average Republic
Western monarchies are monarchies because they have been lucky enough not to have the type of upheaval in their past that cause their monarchies to he overthrown. They have absolutely no effect on our wealth as a nation, or on poverty or food bank usage. India in part is poor partly because of the caste system ( which was taken advantage of by the British) but also because millions of pounds of wealth was siphoned out of the country to ' gift' to the British Monarchy. Most of it they still have. It is easy to average out Monarchy v republic because there are hardly any Monarchies compared to Republics, so obviously there will get on average more poor ones. Especially when the ME ones ( The Queens bosom buddies) are absolute and sitting on tons of oil money.
If you look at the remaining constitutional monarchies in the world ie Sweden, Japan, Jordan, Norway, Denmark, Spain, Luxembourg, the UK, Australia, Canada, New Zealand and the Netherlands and Thailand they are almost all wealthier, more prosperous and more free than the average republic. There are only a handful of absolute monarchies left in the Middle East but even they are richer per head than most of the rest of the Middle East.
India has been independent for over 70 years, it still has billionaires sitting alongside those in effectively absolute poverty. It cannot keep blaming the British Empire
Exactly. No wonder they restored the Monarchy! If they'd done it properly instead of "let's have some deathly dull Puritans in charge' it may have survived.
You don't know who could become President in a republic, that is the whole point, as the US for example found with President Trump. Constitutional monarchy at least provides stability as head of state