Can the GPER unit https://mikrotik.com/product/gper
be used with 24 V passive Poe input. For example with the following switch
MikroTik SwOS Switch 5 Port Gigabit PoE 1SFP | RB260GSP
Because according to the data sheet it says 24 to 57 V. It also says that it allows 802AF.. But this switch is only 24 V passive Poe

It will work with 24V PoE input...
The main problem is the Voltage drop on the cable and on the GPeR.

Depending on the Quality and Lenght of Cable
You may only have 22V at the other end.

This may cause Problems with the GPer.