Ok, I got it to finally work on both sites by combining the following in the Custom CSS field in Helix with Menu Type of "Mega Menu & Off-canvas". This was on joomla 5.4.0, Helix Ultimate 2.2.1:
@media screen and (min-width: 1460px) {
#menu-right {display: none !important;}
}
.burger-icon {padding-top: 17px;}
.close-offcanvas > .burger-icon {padding: 0;}
.offcanvas-menu .offcanvas-inner {padding-top: 0;
}
@media (max-width: 1460px) {
#offcanvas-toggler {display: block !important;}
#sp-menu .sp-megamenu-parent {display: none !important;}
}