These debates only work to sway the tiny percentage of the population who were destined to be on a side but they hadn't been exposed to it yet. Happened to me, but it's doesn't seem common at all.
Discussion
Careful with the labels, they don't translate well across the Atlantic. The "nationalist" is wearing the T-shirt of a far-far-right party that wants the return of the dictatorship that run Spain for 40 years. A bunch of gym bros with a peanut for brain.
In Europe "liberal" means like Mises et all, Austrian economics and small government, unlike in the US where I frequently hear it used with a leftist flavor.
That said, I'm all for sun, steak and steel! But that doesn't correlate with the pic or what you were inferring from it.