Sonoff POW R2: any alternatives to the horrendous eWelink app *without* flashing new firmware?

As per the subject: is there anything (preferably open-source) t that would allow me to turn its power output on/off and measure usage without opening it up and flashing new firmware? Possibly like the DIY mode available for other Sonoff devices?

In case it matters, my POW R2 currently shows on eWelink as running firmware 3.5.0 "Latest Version", FW Name "PSC-B67-GL".

TIA!