Much of the American public seems to have forgotten that the government shutdown started on December 22 when Republicans controlled both houses of Congress and Paul Ryan was Speaker of the House. In fact, Rep. Nancy Pelosi had absolutely nothing to do with the initial shutdown, since at the time she only spoke for the Democratic minority in the House of Representatives.
For two years the Republican Party had majorities in both houses of Congress, yet failed to fund the border wall. In December 2017, Republicans passed major tax legislation without a single Democratic vote in Congress. This shows that when GOP politicians wanted something bad enough, they got it. They didn't fund a border wall because I don't believe they wanted to.
Back in February 2018, Democrats were willing to spend $25 billion on President Donald Trump's wall in return for a path to citizenship for Deferred Action for Childhood Arrivals (DACA) recipients. That's almost five times the amount Trump wants today, but the deal collapsed when Trump demanded limits to legal immigration and the GOP Freedom Caucus refused to vote for “amnesty”.
Suppose the Democrats voted tomorrow to give Trump $5.6 billion for his wall. Then what do you think Trump would do the next time he wanted something?