There is no minimum current limit for 20V output in PD specification. The charger will give 20V even if your laptop use 0A. There is a minimum advertised current value for charger to be considered eg. 45W, which is not what you are thinking.
This is how my native USB-PD powered laptop works. You can already buy Type-C plugs with barrel or square (Lenovo etc.) ends which give out 20V output (I have a few of those as well). So you can use your favorite USB PD charger with your laptop easily. Actually, you can measure the voltage at barrel/pd adapter when it is not connected to laptop and you will find that it has ~20V with 0A current.
The table at Wikipedia at the link you provided is flawed, as it is there without any context. The current values in the table are minimum/maximum advertised values by chargers. A 45W charger should advertise supporting 2.25A at 20V. It is PDF/20 which is in this case 45 / 20 = 2.25
You can get the full specification from USB site (page 602 lists the actual table):
https://www.usb.org/document-library/usb-power-delivery
Here is a screenshot of the actual table from specification with explanation of the values (including the 2.25v etc.):
USB PD Table
Although, you would be well advised to use at least a 60W PD charger. Because charger will enter overcurrent-protection if your non-PD laptop exceeds the charger's maximum current value.