The more i read about me7 functionality the more I ask myself the question if a wideband lambda probe is necessary for a stage 1 tune.

Without changing anything regarding fueling calculation tables you wouldn't need one.

Isn't it enough to log idc after adjusting load and ignition tables?

At partial load the narrowband lambda will do his job and will keep u safe.

At wot, so with open loop, me7 calculates based on maf readings requiered fuel for desired lambda.

So if idc is still good you should be still safe.

Please correct me if Iam wrong.

You can do that way, sure, but you will never know real AFR.
Use at least Innovate tailgate Wb02.

You are assuming the stock hardware is functioning correctly. That is a bold assumption.