As per the title. can any of the currently available smart plugs be controlled directly via a computer on their network using a known protocol, rather than having to use Gurgle's Alexa (don't, won't, won't work for automation anyway) or a 'smart phone app' (exactly the same reasons)?
Will any of the available smart plugs work without a phone or alexa?

mrand31 Can thoroughly recommend these:
https://www.mylocalbytes.com/products/smart-plug-pm?variant=41600621510847

All smart plugs work via a phone app initially. The alexa control is strapped on once the device is set up.
A command issued to alexa is sent to the relevant smart plug app (smart life / tuya /ewelink etc) and it then controls the plug /switch /lamp.
you do not have to use alexa /google.

positor1 The ones I recommended don't have/use a phone app, all that's needed is a web browser.

judgepd
NICE!
That looks like just the thing to use. Far more civilised than all this mobile phone app or other third party dumbing down that's so popular.
Downside is that it'll be yet another programming job to tackle. Upside is that I'm laid up with a broken ankle and programming's about the only thing I can do to keep me sane. 😃
I've ordered four and I'll get to them once I've finished my workshop tools and equipment database program.
Thanks for the link.