I am now at the most interesting (and rewarding ) point - getting the device into OH. I found this link and this link as starting points.
I am fully OK with manually putting in my conf files both items and rules, but I would like to have at least the plug autodiscovered by OH, so I do not need to think about the name and create a things file (up to now empty!).
Does anybody know how/if it works and, if yes, any link to share?
You can enable simple mode in PaperUI but it’s not advised as you may run into issues later when adding more things to OH. Both links you posted are good guides to set up the devices. If you have issues with set up just let us know and we can help.
I have now around 20 different things, all of them implemented with the hybrid method (adding discovered thing and configure items in a file,)… Do you foresee issues in a near future?
If the devices follow the Homie or Home Assistant MQTT topic standards they can be automatically discovered. Otherwise the Things must be created manually.
I believe Tasmota has an option to enable the Home Assistant standard which would make them automatically discover-able. But enabling that used to be hidden somewhere in a console where you had to enter a command. The Tasmota docs will have more information.