Explicitly, from TFA:

> But secure backups aren’t the end of the road. The technology that underpins this initial version of secure backups will also serve as the foundation for more secure backup options in the near future. Our future plans include letting you save a secure backup archive to the location of your choosing, alongside features that let you transfer your encrypted message history between Android, iOS, and Desktop devices.

Yeah, they're definitely fully aware. If they ever do actually get cross device local backup I'll be particularly pleased, several years back the stance was basically "working as intended".

Looking at how long it‘s taking them i wouldn‘t hold my breath!