I have the Ecoflow Delta Pro powering my X1C and during failover it can glitch the printer if the load is high. The H2D would possibly be even more likely to glitch but depends on some things.
I had a lot of good failovers until I glitched a print so don’t risk it now. During a mains drop the printer is running off energy stored in the power supply coils and caps. The higher the load, the faster that reserve is used. If power isn’t restored before the power supply uses its reserves, it’s a power cut.
The Delta Pro switches fast but apparently not fast enough in some circumstances (high load).
The solution for me is to just run the printer from the Delta Pro battery (mains off) so it’s already on battery with no switchover. If I need more juice because the battery is down some, turning mains power back on during a print has not had any problem. It’s just when mains drop and that may or may not be successful but usually is.