Since we don't know what kind of sensors you want, here is the most specific-broad answer I (and maybe anybody) can give you:
The first order of business is to attach a device to the Jetson Xavier that allows for so many GPIO pins. Since I can't think of a single device, what you can do is use multiple devices, like a Teensy 3.6. They have a bunch of I/O pins (around 40 total), AND all digital input pins are interruptible. Then, for your analog input needs, you can use a chip like this to convert Analog to Digital readings into an SPI bus readout. This chip can then interface with the Teensy through SPI. The only issue is the voltage conversion, but Sparkfun also has a logic level shifter chip that can connect 2 different voltage devices. After all that, the Teensy board(s) can all connect to the Xavier through USB or CAN or I2C or whatever you choose. If you need more Teensy boards, add more as needed. At the moment, the Sparkfun website is down (presumably for maintenance, it is a Sunday night), so I can't link the level shifter in this answer now. Basically, your question is a bit broad, but that is what I would do. Also, as @jsotola said, "easy" is relative, and with 100s of sensors, nothing is easy, (please) don't lie to yourself: this is bound to be a wiring nightmare. Companies like Pololu sell wiring equipment so that you can either buy premade wires or make your own, but again: too much opinion/options/not specific in a question.