Voltage (V) is as power brick says.
Current (A) is as the laptop wants.
If voltage is greater than a laptop can handle, the laptop gets damaged.*
If current is greater than the power brick can provide, the power brick gets damaged.*
*In the so-called ideal world. In real world, overvoltage and overcurrent protections may exist.
Also the ratings on components generally are at some percent of their actual safe range (often +/-10%). So you might get away with 20v on a device that wants 19v nominally. Just like AA batteries give between 1.2 and 1.55v depending on their internal chemistry. Feeding extra voltage to something like a laptop which has internal VRMs is likely to produce extra heat in those VRMs. Likelyhood of damage scales with time and external temperature (which is how you can find people sending 1.8v to their CPU/memory when cooling via liquid N2).
Unless you know what components are downstream of the higher voltage, and read their datasheets, it’s best to go with as close as you can get to their rated specs. Except for maximum amperage on the supply, you can pretty much always benefit from throwing a bigger power supply at it (the supply will run cooler, but after a point will be less efficient).
Oh, also remember that wattage (which causes heat death) scales as the square of the voltage (V2r-1). So a tiny amount over the rated voltage can easily fry components.
20v vs 19.2v is a complete non-issue. The BJ size (OD, ID), pin, polarity, etc are all more important. I’m not sure I’ve ever seen a lenovo device that uses a standard 55.5/2.5mm BJ plug like the L13/L15/Minis.
The Librem 14 will almost certainly use a smaller BJ connector in addition to having USB-PD charging. If your Ideapad supports USB-PD, then you can use a single charger for both.