Use Roku Stick with Monitor - Powering off

I'm trying to use a Roku stick (Streaming Stick+) with a monitor, and am looking to find a solution to power off the monitor remotely - help appreciated

This must be a reasonably common problem, but I've had a good search of the message board and haven't been able to find a solution. I've explored a few solutions, each with a fundamental drawback:

A. Custom black screensaver, but that means the monitor is always on - and consuming 35 Watts - rather than actually going into standby mode.

B. RF-controlled power socket - these appear to be on different frequencies, so require their own dedicated remote

C. Wifi/Alexa controlled socket - I'd like to keep the setup as simple as possible and do not want to use voice control.  

D. Purchase a new TV - The monitor I'm trying to use is now a spare, and I've not been able to find a decent, 1080p TV which is 25" or smaller (we're trying to set this up in the kitchen).

What have I missed?!

My understanding is that:

1. unlike on my TV, the power button on the Roku remote doesn't communicate with the monitor in any way (either directly via RF or indirectly via CEC) 

2. the monitor (a Dell U2515) goes into sleep mode ("Active-off") once the input stops

3. there is however no way of turning off the Roku stick - it starts its screensaver after a few minutes of idle.

4. the monitor doesn't ever go into sleep mode because it is still receiving an output from the Roku

Thanks in advance for help.