Absolutely, I charge an ecoflow delta mini with my delta max, the latter being charged by a solar panel. I hope I have answered your question.

You mean the UPS function, the current is simply passed through. (when the battery is full)
If there is a power failure, the EcoFlow automatically takes over the power supply within 30 milliseconds. For normal devices, the 30ms are no problem, but for servers / PCs it's not so tingly. There are other providers who manage 14 -15ms.

Thank you for your reply. I would like to have a small clarification, in case of recharging by the mains while supplying a fridge for example. I would like to know if the fridge will still be powered by the battery in case of a power cut, and therefore of the recharge.
So without any action from the user, for example if the power cut occurs during the night, the inverter starts automatically