Retrospective actions are a vital part of the Sprint work, so they should be agreed with PO and tracked as such.
You mentioned you use a Kanban board. Why not tracking each action as an item in the board? You may want to have a mean to separate these items from the other Stories, but it all boils down to what works better for you.
In our team, we use a ...
A Sprint Retrospective is part of the inspect-and-adapt process. The 2020 Scrum Guide says that "[t]he most impactful improvements are addressed as soon as possible," but doesn't prescribe how the team must implement any given adaptation.
The whole Scrum Team is collectively responsible for working together to decide how to best implement ...
Two cases come to my mind
Is everyone ok with you sharing the information?
Does it make sense to share all information?
Once you clarify that everyone is ok with sharing that information and you decide that it's a valuable information to share, great.
My suggestion in how to share them would be based in a bullet from this answer
Do a retrospectives on how ...