This is before (with no prefetch/preconnect)…
Seems that some numbers are better, some are worse. However, I do see that it loaded the DNS for fonts.gstatic.com at the same time as the request to fonts.googleapis.com.
To compare, here is the results running the following lines in wp_head of Hooks.
<link rel='preconnect' href='https://fonts.googleapis.com' crossorigin> <link rel='preconnect' href='https://fonts.gstatic.com' crossorigin> <link rel='preconnect' href='https://fonts.googleapis.com/css?family=Oxygen:300,regular,700' crossorigin>
Interestingly, you can see using the preconnect in Hooks, that it loads the resources from fonts.gstatic.com and does the SSL connection right there, as opposed to waiting when using the function you provided.