Upgrade from OH2.5.12 to OH3.4.2 (Raspberry 3+ to Raspberry Pi 4+)

I am afraid your are right. I do not want to have usb hub as of now. for me it is important to have clean, stable and reliable home automation system. With OH2 I have been learning. With OH3 I need to clean up this what was not properly done before.
I created new post to gather user experience.