As an alternative, as mentioned already in response to another comment is oksh (https://github.com/ibara/oksh https://github.com/ibara/oksh), a portable version

As an alternative, as mentioned already in response to another comment is oksh (https://github.com/ibara/oksh https://github.com/ibara/oksh), a portable version of OpenBSD's pdksh. It's in the same Bourne shell lineage as bash but is lighter and the completion is simpler: you have to customise it if you want it to work for you, but it's very easy and quick to do.