I’ll try (really I will) not to get tooo nerdy about this, but here’s my set-up.
Admittedly, not been on the camino since 2018 so everything based on 3+-yr old experiences. But the containers have been with me on all caminos from 2010 on.
I try and stay primarily in municipal/paroquial/donativo albergues. Most m/p ones have a kitchen, many have a useable set of utensils (not so much in Galicia). If you’re planning on staying primarily or exclusively in private places I wouldn’t bother with a titanium mug, but a bit of tupperware can be useful for storing soft, cheesey or liquid items like leftovers that you want to eat the next day.
Some places just have a microwave (tho’ most have cooker hob and microwave). However recently opened or refurbished municipals/paroquials often just have a microwave (probably lowers the insurance cost for fire risk?).
The items in the pic allow me to warm drinks or small food items (like noodle packs) on all set ups where there are insufficient utensils. (For those evenings where you arrive late in the rain and don't want to go out again)
The plastic container works in a microwave. The titanium pot can go directly on a stove (because it is single-walled - the double-walled versions aren’t designed to do this). Both containers are big enough to make coffee/tea etc for two - or expressos for many!
Coffee sachets in mercados tend to be decaffeinated. So you either have to hunt multiple outlets in a bigger town, buy a whole jar or bring your own if you need to be carrying an emergency caffeine hit (especially if up early and walking kms before the first café opens).
Likewise a few places stock smallish tubes of condensed milk, but these seem to be getting rarer. If you have to have some milky bit you are best to bring some powder with you.
As far as I’m aware (just checked search engine) here in Europe you can still bring a pen-knife with a blade of up to 6cm / 2.36inches as carry-on luggage. This is easily sufficient for cutting baguettes, veg, fruit etc. There’s a technique for doing this without a chopping board - practice before you leave. Youtube is your friend here.
However even a small pen-knife with a corkscrew will be confiscated by airport security. But you don’t need one nowadays as many wine bottles have screw tops. For those with a cork we now have youtube, which shows it is pretty straightforward to open these without a corkscrew….
Cheers, tom