Am I correct in understanding that TSP, also called Sugar Soap....
Nope. TSP is Tri-sodium phosphate...

So what is in Draino?

The Draino brand drain-unclogger I have seen is a mixture of lye
pellets, and granulated aluminum. When dumped into a drain and
watered, the lye and aluminum react, generating hydrogen gas, quite a
bit of heat, and often some steam. The heat helps break up the gunk
clogging the drain.

"Red Devil" brand drain-unclogger is just lye, without the aluminum.
If I recall correctly it even comes with instructions for making lye
soap, using lye and fat.

--
Dave Platt AE6EO
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