The answer is to use radio triggering. With a Godox TT600, that would mean getting another Godox unit to act as a radio transmitter on your camera's hotshoe (a Godox TTL capable speedlight, or one of the 2.4 GHz transmitters with "X" in the name that's for Nikon (e.g., the X3-N or XPro II-N). The TT600 has a built-in radio transceiver that can work with other Godox X system radio gear.

You'd also need to switch the TT600 from the S1/S2 optical wireless modes to its radio slave mode. With Godox speedlights a horizontal lightning bolt button can change how the flash is triggered.

1. Hold down the MODE/lightning-bolt button for two seconds until the radio antenna icon blinks.
2. Turn the control wheel to set the radio to Off / M (master) / S (slave). Press SET when the S appears to set slave mode.
3. The use the GR/CH button (pressed for group, held down for channel) to assign a group and match the channel setting on the transmitter.
4. Make sure ID setting is off on the transmitter, since the TT600 cannot use ID codes.

This will give you remote firing (under any lighting conditions), remote M power adjustment by group, group on/off, and HSS over radio.

Optical slaving (using S1/S2) can be overwhelmed by brighter ambient light levels, so that the range and line-of-sight requirements for optical slaving get much more stringent. Optical slaving works well, as you've found out, in studio conditions (lower ambient, lots of bounce surfaces) but can become much less reliable with a much smaller range outside in bright sunlight. Which is why most people prefer using radio triggering.