You could probably do this using a Part-15 device, but there are very strict limitations on such a device. Things like no interference with licensed users, extremely low power levels, short distances for coverage are just a few. For driveway gate activation it would probably be simpler and more reliable to use a buried wire connection (after all, you will already need power so just run some control cables and you'll be all set). You could probably also do something pretty simple (and cover a wider range of events) using a small computer in a waterproof box with a wifi connection back to where you will want to monitor those events (perhaps using a directional antenna for better range and less chance of intrusion).
Examples of some events you could monitor this way is full gate status (open, closed, moving, stopped but not at an end point, etc.), temp (72.5 degrees outside, motor temp 94.2 degrees, etc.), flooding (perhaps with multiple sensors this could include area a, area b, etc. or even level 1, level 2, etc.), motion detection (like the flooding could include multiple sensors if desired), let your mind wander since your options are only limited by the number of sensor connections on your control box(es).
For some of these functions you can probably purchase off-the-shelf devices to cover them. Things such as the Davis (
https://www.davisinstruments.com/weather-monitoring/) line of weather centers, especially their agriculture line, (cover the temp pretty easily (it may say indoor and outdoor, but you'll know it really is for outside and motor), and with some add-on devices you can do the flooding, light/dark, etc.. For a lower cost (but you'll be more limited on what you can easily monitor out-of-the-box) their lower end/lower cost models can do part of what you need so you'll need to have less customized for you. The Davis devices use part-15 transmissions from the sensor(s) to the display station (as an example of what part-15 can do for you).