If you believe France is a useful single doppelgänger you honestly need to read a bit more.
Before 2016 the UK was more open and more finance-heavy (about 7% of output vs 4%), it ran a current-account deficit of about 5% of GDP (France was near balance), and its labour market was more flexible (about 74% employment vs 64%).
France was also in the euro, more state-cushioned (public spending about 57% of GDP vs 40%) and more EU-oriented in its trade.
On almost every channel Brexit worked through (sterling, investment, services trade, migration), France would have responded differently.
I think you’re picking data to suit your opinions. And you’re diverging from the vast majority of economists when attempting to compare the counter-factual case. That alone should give you pause.