Let's break down the requirements for GFCI protection based on the NEC (National Electrical Code), since that's the governing standard in the US (and widely adopted elsewhere).

NEC Considerations (and why it likely NEEDS GFCI) NEC 210.8(A) Dwelling Units

This section doesn't apply since it's not a dwelling.

NEC 210.8(B) Other Than Dwelling Units

This is where it gets relevant. It requires GFCI protection for 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground, 50 amps or less in specific locations. The relevant one here is usually:

(6) Toilet Rooms

GFCI protection is generally required for receptacles in toilet rooms in commercial, industrial, and institutional occupancies.

Why GFCI is Almost Certainly Required

Even though it's not a "wet" location in the sense of a shower or sink being present, the presence of a toilet means this will probably be considered a toilet room. Therefore, unless there is a VERY specific and highly unlikely exception, the 20A, 120V receptacle for the Incinolet will need GFCI protection.

Important Considerations & Recommendations1. Local Codes and AHJ (Authority Having Jurisdiction)

This is the most important point. The NEC is a model code. Your local building codes may be stricter or have specific amendments. Always consult with your local building department or electrical inspector (AHJ) for a definitive answer. They have the final say. Tell them exactly what you're planning to do (waterless toilet, no other plumbing, etc.) and ask if a GFCI is required.2.

Manufacturer's Recommendations

While the Incinolet documentation may not explicitly require GFCI, it is generally good practice to follow any safety recommendations they make. You could also contact them directly to ask about GFCI.3.

Best Practice

Even if not strictly required by code (which is unlikely), GFCI protection adds a layer of safety. Given the potential for moisture (even from cleaning, spills, or humidity) and the fact that you're dealing with electrical equipment, it's a prudent safety measure.4.

Type of GFCI

Install a GFCI receptacle (the type that's built into the outlet) at the location where the Incinolet will be plugged in. A GFCI breaker at the panel would also work, but the receptacle is generally more convenient for testing and resetting.

In Conclusion

Given the NEC requirements for toilet rooms, it is nearly certain that the 20A receptacle for the Incinolet will need GFCI protection. However, you must* confirm this with your local building department or electrical inspector (AHJ) to ensure compliance with local codes. Installing GFCI is a good safety practice regardless. Flag for review