mgcv::bam with monotonic constraints

Dear List,

I need to fit a GAM to a large dataset (`mgcv::bam` does this), but
ensuring that some covariates have a monotonic relation with the response.

`mgcv::mono.con` with `mgcv::pcls` seem to do this, but only for
`mgcv::gam` (not mgcv::bam)?

I'd really appreciate any pointers!

Regards,
Axel.