Go for the nanopresso, you won’t regret it.
I have a little flask that screws directly on, but I don’t think they sell that anymore. A normal flask will work nearly as well.
I also bought the Nespresso add-on, as this is handy on a long trip out. I’d also buy a decent portable cup, as using the included cup/cap is a bit plasticky.
It has served me well. A while ago my espresso machine broke, so for a time I just had the nanopresso. It’s a bit of a faff first thing in the morning if you’re brewing for more than one person, but it does make a good coffee.
Has anybody tried the picopresso? https://www.wacaco.com/products/picopresso