Had to look up the post from February 2019, no I gave up back then but there was a new fork of OpenConnect which does the SAML redirect (well on x86 linux) and there is gp-saml-gui also now.
Haven't tried any of those on OS X or Linux PPC however in the past years,had no real use for it , just to show off that my older machine could connect to our work VPN, Getting work done on all those Java/Flash based GUI interfaces however would have not been possible on a PPC machine, and since all stupid vendors are moving away from CLI configuration ....