HDMI CEC can do this automatically, no special power strip required—if you're lucky and none of your devices implement it poorly.

[EDIT] Oh nevermind, this is about making sure nothing can wake up and phone home when not explicitly powered on.

i've had the belkin version of this for some years, the Conserve Smart AV (unfortunately discontinued): https://www.amazon.com/dp/B0085Q722A . i have my tv as the master switch and my apple tv on an always on outlet so that it's the only other device that can wake my tv via CEC (it's my home hub as well, so need to keep it powered continuously). (edit:) oops, just remembered my A/V receiver is also plugged into an always-on outlet and can turn on the tv via CEC as well.

i also have a few of the Conserve Switch models, which have a wireless radio switch but is otherwise not "smart": https://www.belkin.com/conserve-switch/P-F7C01008.html

both have been handy and going strong. i'm still puzzled why belkin basically discontinued the conserve line of products. seemed like the logical launch off point for their smart home stuff (now under the wemo brand name).