GPU upgrade mandatory on iMac (21.5-inch, Mid 2011) ?

I want to upgrade my iMAC to catalina and in understand there is an issue with non Metal GPUs which is what i have.
I read somewhere that openCore is able to work around this but i wonder if it's worth trying or ill just hit a bunch of issues when working this way.

So, is it better to upgrade the GPU and is there any guide around ?
I will likely go ahead if it's not too complicated. i was already able to increase the RAM and upgrade to SSD, so im okay with plug-and-play, but low level tinkering is too much hassle for me :).