Load a SPA webpage via AJAX

I'm trying to fetch an entire webpage using JavaScript by plugging in the URL. However, the website is built as a Single Page Application (SPA) that uses JavaScript / backbone.js to dynamically load most of it's contents after rendering the initial response.

So for example, when I route to the following address:

https://connect.garmin.com/modern/activity/1915361012

And then enter this into the console (after the page has loaded):

var $page = $("html")
console.log("%c✔: ", "color:green;", $page.find(".inline-edit-target.page-title-overflow").text().trim());
console.log("%c✔: ", "color:green;", $page.find("footer .details").text().trim());

Then I'll get the dynamically loaded activity title as well as the statically loaded page footer:

However, when I try to load the webpage via an AJAX call with either $.get() or .load(), I only get delivered the initial response (the same as the content when over view-source):

view-source:https://connect.garmin.com/modern/activity/1915361012

So if I use either of the the following AJAX calls:

// jQuery.get()
var url = "https://connect.garmin.com/modern/activity/1915361012";
jQuery.get(url,function(data) {
    var $page = $("<div>").html(data)
    console.log("%c✖: ", "color:red;",   $page.find(".page-title").text().trim());
    console.log("%c✔: ", "color:green;", $page.find("footer .details").text().trim());
});

// jQuery.load()
var url = "https://connect.garmin.com/modern/activity/1915361012";
var $page = $("<div>")
$page.load(url, function(data) {
    console.log("%c✖: ", "color:red;",   $page.find(".page-title").text().trim()    );
    console.log("%c✔: ", "color:green;", $page.find("footer .details").text().trim());
});

I'll still get the initial footer, but won't get any of the other page contents:

I've tried the solution here to eval() the contents of every script tag, but that doesn't appear robust enough to actually load the page:

jQuery.get(url,function(data) {
    var $page = $("<div>").html(data)
    $page.find("script").each(function() {
        var scriptContent = $(this).html(); //Grab the content of this tag
        eval(scriptContent); //Execute the content
    });
    console.log("%c✖: ", "color:red;",   $page.find(".page-title").text().trim());
    console.log("%c✔: ", "color:green;", $page.find("footer .details").text().trim());
});

Q: Any options to fully load a webpage that will scrapable over JavaScript?