Neither a gym nor gadgets are needed to stay fit! There are many resources on "body weight" exercises that you can do anywhere, or check out one of the many "7 minute" workout apps.
A personal trainer can help you come up with a good routine and make sure you're doing the exercises correct, but you can also DIY (assuming no prior injuries or other issues).
Gadgets like free weights, bands or step platforms can be added later, to make the exercises harder, not to make exercising less effort
In addition to strength training, there's also "cardio" exercise, see e.g. these recommendations. If you get an exercise bike, you can read a book while working out, or perhaps you can incorporate some (fast) walking into your daily routine...