I suppose the “nation state” is “The United Kingdom of Great Britain and Northern Ireland” so in that definition, no, England is not a country. More of a “province” within the UK.
Scotland Wales and Northern Ireland having devolved governments make it more confusing, as what’s left over is England… but England doesn’t have its own devolved government…
And then we get into the “Holland” vs “The Netherlands” confusion – Holland is a province within The Netherlands, but most English folks are sloppy and call the whole country “Holland”, even when referring to, for example, Zeeland
America: North America, South America, Central America or The United States of America? yada yada yada