Hi Laura,
I am afraid that this is not possible in Muse at this stage, I will recommend that you post this on our ideas section over here, https://forums.adobe.com/community/muse/ideas, and let our devs team know of this requirement.
As a work around I will suggest that you create a dedicated page with this panel opened when you publish and link that page with the text that you want. Let me know if you need more clarification on this.
- Abhishek Maurya