But have read that its not good to put those in if chemicals have been used.
(and realize probably it might not have been a good idea to use the chemical anyway)

The sink does very slowly drain so am guessing/hoping that the chemicals are all
gone, but not sure if they might still be present in the clog whether in jbend/ptrap
or further down the line (toilets and showers in same room drain ok)

===> Do you think its safe after one week to try the baking soda and vinegar ?

PS I would have removed the jbend first but the sink is a pedestal sink, and the pedestal
almost flush to the wall, and one end of the jbend is partially inside the pedestal itself;
and with my lack of experience, felt that it might have not been possible to put the jbend back.
As it is, a mirror is needed to see that end of the jbend inside the pedestal.

Thanks for your suggestions and comments.

Here's the thing: Bathroom sinks get nasty glopps of soap, hair, shaving stuff, tooth paste, etc. + probably some growing stuff. Nasty, to be sure. A big part of the problem is that there often isn't enough water to wash it all the way down the drain.

Remove the stopper if you can. Block the drain and fill the sink full with warm, soapy water. Open the drain and plunge it with a sink plunger while keeping the overflow blocked with a damp rag.

That should remove most of the nasty stuff that's clogging the pipes. Repeat until you have a fast running drain again.

Remove the stopper and look down the line.

Remove any junk you see.

Also check the trap for crud.

Some of the Chinese drain assemblies do not allow for removal of the stopper without unscrewing the actuator arm that enter the back of the tail piece.

And trying every half a** thing to avoid a real fix.

There was enough room to hook it up, there is enough room to take it apart.