See this recent conversation in terms of protecting inputs. Do you think the 3.3V outputs will be enough to trigger your eurorack modules? You would probably need a smaller output impedance in that case, as a large series resistor (such as the 33k in use in Pepper) would decrease the effective input seen by another module's input. You could have something like this:
Where D1 and D2 are Schottky diodes which will short any over (or under) voltage to the power rails. The current through the diodes is limited by the 1k resistor in series.