Is there a way, method, obscure website, that allows me to best choose my Zwift bike that matches (close as possible) my IRL bike?
id like to do big Zwift climbs AdZ, ven-top, not on the games most lightweight fancy pants bike/wheels but on one that would give me a more realistic (as possible) climb time, before I do the climbs IRL
I don’t think so - IRL bikes are totally unrealistic versus Zwift. 
It’s quite well known in Zwift that even very fast / light IRL bikes are quite slow in Zwift.
I would just go for whatever is the current best available to you wheels/frame combination and hope it doesn’t get nerfed later on.
Focus on average power and particularly for climbs, the watts/kg instead.
You might be able to get a reasonable time estimate for the IRL climb from bestbikesplit.com and then use zwifterbikes.web.app to pick a bike/wheels that gives you a similar time
I have a number of my bikes drivetrains configured on my Kickr bike, it’s nice to have a rough comparison between zwift bumps and outside bumps.