The truth is, if the trip is short, I end up just taking the ipad and focus on consumption. If I take the Surface, I always take the iPad; there can never be no work withot play. My spreadsheets dont function on the Ipad as there are macros and scripts and it relies on multiple spreadsheets open simultaneously, plus links to word and presentation files are broken [don't dynamically update].
Yes I cannot see a time when the iPad will be able to do what I want to do or the Surface. It is only my opinion, but it seems Apple is stuck between a rock and a hard place, i.e. making MacOS touch friendly is next to impossible and making IOS a fully featured OS is pretty much the same.
I am in the same use scenario as you are.
iPad mini as a minimal and iPP 12 as a bigger minimal for longer trips, which does fine for most consumption of work and private info + minimal emails via soft keyboard. I will sometimes take my non-ten-key Apple keyboard and the Trackpad, if I know that I will need to answer many emails or will have down time.
For anything else, especially if I anticipate having to work on office documents, I take either a surface-Go or my MBA, as I just want to make sure I have the normal tools for the job. The USB-C cables becoming more common, such as a USB-C to Lightning cable, allows me to consolidate chargers, so that's not really an issue. Throw the Trackpad into the keyboard sleeve, and that doesn't bulk either.
The Surface-Go, although under-powered for heavy multi-tasking, does fine with things like Zoom or most of the office suite, so the mini + Go is my normal kit. The Go may get replaced by my 2020 MBA.
On-topic of the newly released Magic Keyboard .. I love the concept and hope it continues to get better.
It just does not fit my use case currently because I tend to have a laptop nearby all the time while at home or office, and do not anticipate using the iPad as a desktop device.. while, it is a bit too heavy for my liking for travel (the keyboard and trackpad combo weigh less than the MK for iPad 12). It would be a nice set up for desktop use of large iPad I think, where bluetooth switch will not be necessary.
If I anticipate having to type on my lap, I would bring a laptop anyway as per above, and I have also gotten pretty good at typing emails on my iPhone, sadly.
Everybody's use case differs, so IMHO.