According to Steamspy the pc version has sold just 3.860 units.
After being out for 10 weeks on #NintendoSwitch, INVERSUS has sold more copies than it has in over a year on Steam! (and it has been through multiple large winter/summer/etc sales on Steam)— INVERSUS (@InversusGame) December 12, 2017
Hypersect also indicated that the Switch version of Inversus Deluxe is quickly catching up to the PlayStation 4 version, which is also more than a year old:
PS4 has also been out for a year and did far better than PC. Switch is on trajectory to overtake but not there yet. Xbox is least populated atm.— INVERSUS (@InversusGame) December 12, 2017