I’d also like this option very much.
I am only using left side panel for design reasons but would love to have multiple panels on left side.
Ex: I’d use one for subscribe form as I am doing now and then another below it for putting my external links of interest which I don’t really want to be visible at all times.
There is another plugin that offers multiple panels but because it makes me add php coding to my footer, it breaks native plugins from the theme I use. Maybe it’ll help you though
https://www.slrlounge.com/side-tab-wordpress-plugin-free-slr-lounge-download
