Was looking for something else and ran into what seems like a really nice bt4 ergonomic keyboard by Microsoft for $34 when it's usually at least $80:
https://www.cdw.com/product/microsoft-surface-ergnmc-kybrd-cmmr/5548723?pfm=srh
https://www.cdw.com/product/microsoft-surface-ergnmc-kybrd-cmmr/5548723?pfm=srh