Sad to say, but the makers of loudspeakers are not giving us the SPL of the items for sale. SPL is the Sound Pressure Level and and should represents a real measure of how much sound can come from a loudspeaker without heavy distortion or damage to the unit.
Example:
https://www.jensentone.com/frequency_response_comparison
Even specs like this don't tell the whole picture. These measurements are taken with the speaker in an anechoic chamber (basically an acoustically dead chamber). It doesn't represent how the speaker will perform or sound in YOUR room. The dynamics of the room play an enormous part in determining how a speaker will sound.
The retailers are not making it easy on us. To truly judge any speaker requires YOU to listen to how it sounds in YOUR environment. Just looking at the numbers won't do it. Frankly, computer speakers are strictly a commodity to me. I buy them based on price with little regard for their fidelity. Fortunately, I'm not a gamer so cheap $20 speakers are all I need.
If I wanted decent sound from my computer, I would get a good set of headphones.