Show current play speed in after effects

You can do it with expressions on the time remapped layers: create an empty text layer ctrl/cmdalt/optshiftt. Alt-click the Source Text stopwatch, and use an expression like:

var s = thisComp.layer("some layer").timeRemap.speed;
"X" + Math.round(s * 10)/10 //limits the result to one decimal place

The time-stretched layers are more tricky. The stretch property isn't accessible to expressions, but what you can do is use the sourceTime() function. This gets the time of the source footage. If your layers start at the beginning of the source then this expression would work:

var s = thisComp.layer("some layer").sourceTime()/time;
"X" + Math.round(s * 10)/10 //limits the result to one decimal place

if the layer source doesn't start at the beginning of the comp then you'd have to do some extra maths, like subtracting the in-point, or to make it easier you could pre-comp the source layer with the text overlay and make sure the precomp has the source footage starting at the beginning of the comp.