Hey @jf20 ,
Is it a standalone server?
if so here is an article: https://www.starwindsoftware.com/blog/how-to-upgrade-esxi-6-7-to-7-0-without-vcenter
CLI process: https://www.nakivo.com/blog/how-to-upgrade-from-vmware-vsphere-esxi-6-7-to-7-0/
Because you are using sd card check this article too.
Thanks for the replies. Seems pretty clear cut. Would really like to know what kind of experience it has been for folks who are still using SD cards on version 7U3?