Hi. Is there any cell in sky130_fd_sc_hd that can be used to make an input pull-up or pull-down?

The cell

sky130_fd_sc_hd__conb_1

has a 2.4-square long poly resistor from HI to VPWR and from LO to VGND. But at 42.2 ohms per square, that's only 100 ohms. The high-resistivity options have large spacing requirements for the implants and don't fit inside standard cell dimensions (I think---I haven't actually tried). Your best bet is to instantiate a 5k ohm resistor outside of your digital block.