For me the best way to use MFF2/eSIM/eUICC (embedded SIM | Embedded Universal Integrated Circuit Card) would be via
CLI
So for example on Android we can do it via QR code or via Activation code (as per manual here at EE)
https://ee.co.uk/help/help-new/getting-started-and-upgrading/setting-up-an-esim/how-do-i-use-dual-sim-for-samsung
/lte esim add 0 “LPA:1$ee.pr.go-esim.com$ABCDEF1234567890ABCDEF1234567890$$”
There could be a option to load the PNG QR code as well via Web Interface…