>A microwave only work with an on/off cycle.

That may be changing soon because of solid state microwave/rf-heating:

Solid State Cooking Oven Uses RF Energy, 1m31s

[1] https://www.youtube.com/watch?v=C6Xg1UAwutc

Goji Food Solutions Solid State RF Cooking Demonstration, 2m35s

[2] https://www.youtube.com/watch?v=fg-UtHjkkfM

[3] https://www.popularmechanics.com/technology/infrastructure/a...

[4] https://www.electronicsweekly.com/news/design/the-future-of-...

[5] https://appliancebuyersguide.com/mieles-dialog-oven-brings-r...

[6] https://thespoon.tech/miele-introduces-the-dialog-a-high-end...

[7] https://www.infineon.com/cms/en/applications/consumer/home-a...

[8] https://www.digikey.com/en/product-highlight/i/infineon/micr...

[9] http://www.gojifoodsolutions.com/

tl;dr essentially a beamforming solid state microwave phased array

edit: removed one double link