My travel kit should be in its final form at this point. You can choose between AeroPress, espresso-style AeroPress, and regular drip coffee. All fits in one small waterproof bag from Skog Å Kust. I sometimes also pack cups depending on the destination.
The first rule of good coffee brewing is to grind when you brew, which is why I carry a manual grinder.
You will need access to boiling water.
AeroPress, the main brewing method, avoid the AeroPress Go because the Fellow Prismo doesn't fit, and it's bulky.
Fellow Prismo, when you want a more espresso-style beverage.
Porlex Mini, a small but mighty grinder that fits inside the plunger of the AeroPress!
Basic Scale, or any accurate and fast scale really, get one that goes to at least 1kg so you can make substantial drips.
AeroPress filters, and Altura Disc if you like it. It's a little messier than paper filters, but useful if you run out of paper filters or don't want to carry them.
Miir Pourigami or Munieq Tetra portable drippers. The Snow Peak Field Barista is a tighter fit because it doesn't fold flat, but still workable.
Optionally, you can also carry a thermometer, if you need or want accuracy.
Skog Å Kust DoppSåk - Small, really well built and inexpensive, there's even some space left for beans.
...and I don't know if it's dirty secret or not but Starbucks Via Instant Cold Brew is pretty good in a pinch