I don't think you can do 4Hi while moving, I think you need to be stopped and in N.
You could just leave it in 4hi all day. 4 Hi with your 4th gen basically means AWD. So it will be like any other AWD subrau, xdrive, Quattro etc.. etc...
Then you can hit the center diff lock on and off pretty much any time while driving. This will take you into true 4x4 mode. This means that unlike the 4Hi AWD mode, you
CAN NOT drive in this mode all day on the streets, especially if the street is dry, and you won't need it for rain, light snow, even heavy snow usually. So turn it on if you need it, but then turn it off once you don't need it anymore. If you drive slow enough and be careful you won't really need it on the street. It might come in handy to make your way in or out of a snow covered parking lot, or a street parking spot after the snow plows have buried you in. something like this.
https://youtu.be/33LXlrqNm7Q
I will activate the center diff lock on the fly sometimes if the snow plows are pushing snow away and create mounds in between lanes or at intersections. I activate, and plow through, then deactivate. And when I say plow through, I don't mean launch myself into it, I mean just drive in with a little extra momentum. 4runner is a 5000lbs beast. It doesn't need much launching to break snow up. And you don't want to leave your plastic bumper behind.
Most front wheel drive cars get by winter snow pretty decently. What might stop them is the clearance with heavy snow fall. So with the 4runner you pretty much have the clearance issue solved.
You will be amazed at the control with center diff lock on. But....do not forget to turn it off when you don't need it. It can potentially bind and cause major problems. so don't forget to turn it off.