I want to run vista on TX1/RX1, elrs on TX3/RX3 and uart6 in ports available, but no solder pad TX6/RX6 on fc. Planned TX6/RX6 will be used for GPS. Can it be remapped on the SBUS and LED_Strip solder pads? Thanks in advance for those who can answer.

The SBUS pad will give you an inverted signal which is why remapping it will not help. LED_strip can be remapped without issues.

You can try and softserial the sbus and led_strip pad since softserial can handle inversion and use that for a GPS connection. Softserial is much slower than a proper UART but should be suffering for GPS stuff.

You can also try a single wire GPS connection connecting only the TX wire (connected to a remapped led_strip pin as a RX) but it may cause issues with baud rates.