I use chromium based browser and applications so don't get to enjoy the benefit of the power efficiency gains of safari sadly.

Geat to know this about your experience with thinkpads. Due to your familiarity with multiple such devices would you be able to recommend a starting point for someone who wants something light with budget not being a constraint?

The new x13 Gen 6 AMD with a U-series CPU and, ideally, configured with the 70Whr battery looks very nice. Should be less than 1 kg, similar to a MacBook Air.

I've used the previous generation, and it's possible to get 10 hours of use on battery with some tweaks.

It's a very popular model, so it's well tested and everything should just work with the latest kernel.