The current gtag.jswill support the functionality of GA4, but we do have it in our queue to add a GA4 tag template. I will keep you posted here when it's released. Hopefully some other users will be able to chime in on any success they've had with it. Let us know if you have any other questions!
Just wanted to let anyone know who is watching this that the GA4 tag is in beta. Learn more here: https://community.tealiumiq.com/t5/Client-Side-Tags/Google-Analytics-4-gtag-js-BETA-Tag-Setup-Guide/...