Dear all / whoever in angst of this issue RE: Sidebar Nav / Vertical nav in SQ 7.1,
I have tried my best nearing an entire month around-the-clock; at liaising with various member/s in and outside of the forum clarifying whether or not vertical navigations are pragmatically possible on PERSONAL subscription plan. At least without luxury assistance of plugins or coding injections via Business plan or above.
Unfortunately, so far ~ all alternative workarounds seems compromised. All efforts points to a likely "no". Unless one is truly willing to put their necks in the sand and grind things through manually themselves.
The best tutorial I have so far sought upon is here. But beware: this solution is halfway complete and/or half-baked. You cannot properly display all icons, nav items and cta-button ALL ON simultaneously. And you must find a way to revert vertical menu BACK TO horizontal menu if it is in mobile environment.
Squarespace® sadly brings their 7.1 an ambivalent direction. It is one step forward, three step backwards. A step forward for those who are completely unaccustomed to web design. Three steps back for everyone else - that we have to tinker, troubleshoot and find workaround alternatives far too exhaustive, and unnecessarily numerous-jumping-through-hoops. I fear for the "what-if" scenarios - what if 7.1 were a mandatory global upgrade, like what they did from V6 to V7?
Many thanks to @tuanphan for charitable efforts. I am not a developer hence please consider any or all workaround discussion a subjective one at best until you have proven to your existing needs and environment~ that it indeed works in all cases.
Hopefully they pick this up,
AW85.