Hello, there is quite detailed chart for clearances required between SMT components for PCB assembly:

https://jlcpcb.com/help/article/SMD-Components-Minimum-Spacing

However, I do not see any advice on clearance for THT components (eg. screw terminals, THT switches with knob axle).

I suppose I could get only the SMT parts mounted, and get some equivalent THT parts elsewhere to solder them by hand. Then there would no clearance problem because of tooling limitations.

However, that's only suitable for test samples or very small number of PCBs.