What is the opinion of Reddit about the
NPKC HHKB Keycaps PBT Cherry Profile Fit Cherry MX Switches Top Print or Blank for HHKB 60% Mechanical Keyboard(White-Red Mix)?

I would be very careful about ordering a keyset. Get one that is specific to HHKB and MX stems. You can find one on Amazon for example. Ebay and AliExpress are the other 2 vendors that come to mind. Many HHKB boards use Topre switches, which are not compatible with your switches, so take some time before you order.

I would also order some dielectic grease to lube your stabilizers. It’s not mandatory, but clipping and lubing your stabilizers will really help the sound and feel. You can find a youtube video on how to do that.

If you don’t have a good set of small screwdrivers borrow or purchase one.

And don’t feel bad about asking questions. You will save money, effort and hours of frustration if you ask before you purchase.