For strength, look at gymnastic type exercises. Plenty to do without any material and working on the principles of decreased leverage. Try to do a planche or strict handstand push up and you will maybe notice that you could get stronger doing this kind of workout. Overcoming gravity book is a good reference but there are plenty others over the web and youtube. GMB is also good if you like more guided approach and programming supported by video.
Pistol squats are also a good movement to make you realize that body-weight training can be challenging. Then if it becomes too easy, try doing it while having a weight in your hand (a book or whatever you have at hand)
You can also use bodyweight movements to increase strength endurance (instead of strength, using higher repetitions range).
For metabolic conditioning, you can always go running and use different pacing to target different energy system (sprint, treshold, long slow distance, intervals). Sprinting up a hill can also serve as a strength workout.
Eventually, you can use this time to work on things you avoid when you have access to everything e.g. flexibility and mobility. I always pack something to foamroll and resistance bands in my luggage when I travel so that I can use them to work on my mobility/flexibility
