No, I didn t find a solution. The abnormal was the always high signal from the soc to enable 5V charge line to the right JoyCon rail. Normaly it is switched on after JoyCon detection. I also had a short on the rail due to light corrosion on the contacts.
At my Switch with the JoyCon issue the 2101-0001 error is the bigger problem, so I didn t test further on the JoyCon issue… 