CLI3 + Polaris Page>backAction (migrated from breadcrumbs) - How to write url?

In the migration from CLI2/polaris breadcrumbs to the CLI3 polaris/backAction, the url target of the back arrow on app pages has been totally changed.

It used to be a function, which was compatible with the “redirect.dispatch” function … but now it seems the url must be a string.

How can I format this link now, without hardcoding my store name into the url? Is there a environment variable I can use in my frontend app to get the store name?

Thanks! jb

Still have this problem/question. Anyone have any ideas? thanks jb