Bit of googling suggests this is a whole, fascinating world of little improvements. However it's also both constrained and pushed forward by what's road legal.

https://www.volvotrucks.co.uk/en-gb/news/insights/articles/2... : removing mirrors allows for much smoother cab airflow

https://go2stream.com/blog/aerodynamic-truck-legislation-rea... : UK legalization of fishtail-like devices

https://www.kudauk.ltd.uk/aerodynamics-explained : Kuda on the UK allowing higher loads, and therefore benefiting from extra wedge devices on the top of the cab.

I'm sure there's a lot more out there. The eventual switch to electric will probably come with another round of aerodynamic improvements to maximise range, as with cars.