Some things are BEST to keep a secret and kept under a rock or better yet in a garbage pail for toxic and useless products being pushed on the dummies willing to spend their money on snake oil sales. IMHO
For clearing hard stoppages such as roots or rags a cable is the way to go
For clearing grease, soap deposits and other soft stoppages Water Jetting offers one of the safest ways to restore full flow as what is safer for drains, pets and children then POTABLE water plus it works and is cheap , readily available in civilized countries.
Hercules company makes outstanding drain cleaning chemicals but some contain sulfuric acid and should be considered as a last resort used by professionals
I found most over the counter drain cleaning chemicals are as useful as water with food coloring added.
The fools who buy chemicals to kill roots in drains fail to read the find print and it states "have the sewers and drains snaked out yearly" so why waste your money on chemical treatment?
If your dealing with a professional master plumber they will never resort to pushing chemicals as part of their drain and sewer cleaning services. The reason many franchise handymen push drain cleaning chemicals is to supplements their commissions