Signal's official Android app does not support being linked, only the iOS and desktop apps support that. This is why I use Molly.
I would ideally want to not have one device being the master and the rest linked to it (e.g. Element can do that for Matrix) but that might be a too big change. And as far as I know Molly does not try to solve that.
There's a deliberate nit in Signal that you can't have it on both an Android phone and a no-sim Android tablet; both take turns trying to seize the role. Apparently Molly can handle both.
I would ideally want to not have one device being the master and the rest linked to it (e.g. Element can do that for Matrix) but that might be a too big change. And as far as I know Molly does not try to solve that.