I used a can of this on my old Ramcharger to try to get it to pass the NOx emissions when they added that in the DFW area. It cleaned up the piston tops well from what I could see through the spark plug holes. You might have to put in new plugs after cleaning it out.

GM top engine cleaner would dissolve the carbon balls on the old Chevy Citation 4 cyl engines. It would rattle like ball bearings were in the combustion camber. I`m not sure if it is still available.

I knew guys to pour a can of this down a carb with the engine running...mad science!

https://www.bonami.com/product/bon-ami-powder-cleanser/

Back in the 70's I saw a guy dump Bon Ami down the carb to get the rings to seal and the engine to stop smoking. I thought he was nuts, but it worked. I don't know about using it to clean carbon out.

I watched guy at wrecking yard pour water in one although it worked well the bottom of the motor exited the block

Gently guys GENTLY

I’ve CLEANED UP two high mileage motors using water injection.... Spearco brand ....

Well I didn't try the trans fluid yet but going through my old chemicals I found a can and a half of Ford Motorcraft "Tune-up Cleaner" which is similar I think to the Mopar combustion chamber cleaner. Ran both cans through and got a little smoke nothing too wild. Checked with the borescope after, the tops of the pistons are probably 75% clear but I can see parts of the combustion chamber on the head are still a bit thick. Also with the exhaust vlve open its pretty chunky in the passage for what I could see. m Still wants to ping a but under WOT but not as bad. Maybe another dose of something and a good hour on the highway might sort it out.

For valve cleaning this seems to work well
BMW recommends it

https://www.amazon.com/Liqui-Moly-Ventil-Sauber-Cleaner/dp/B00295G91S