Required to migrate to webExtensions: add multiple Browser_action with custom content

I maintain this add-on https://addons.mozilla.org/en-US/firefox/addon/bitcoin-price-ticker/

To migrate from add-ons SDK to WebExtensions I need to add multiple widgets to the navigation bar and the content of each widget is an HTML document with its own style and content.

The closest thing I found in the new webExtension APIs is the Browser_action but it only allows to add a single icon to the navigation bar, the style is barely customizable and not suitable to show a price ticker text with 5+ digits.

Is there any plan to add any widget with similar features to the existing CustomizableUI.createWidget() ?

Thanks!

For reference, here is how I create an HTML document for each ticker: https://github.com/sebaslogen/bitcoin-price-ticker/blob/master/index.js#L417