API to set the charge rate?

I have an unusual case where it would be handy to have a ‘charge now’ API so I can set the charging rate. Is this possible?

My use case is that I have Amber’s smart shift enabled. When the price goes negative it stops export. Which is mostly helpful in less I’m trying to charge my car. If there were an API I could use my Home assistant to monitor negative prices and ‘ set a charge rate, that would either use solar, drain the battery or buy power, but at least I would have a charged car. When the price goes positive it would be nice to return to Auto. I can use HA to set a charge rate that doesn’t buy too much nor drain the battery too much. Currently O effectively do this manually, but sending commands would be nice.