That sounds very promising. That has always been a major annoyance to me. I don't think i have every owned a laptop with linux where I actually trusted that it would still have battery the day after if I just closed the lid.
That is basically the opposite of what you want. 'Modern suspend' is why you burn battery with the lid closed, overheat your laptop when it's closed in a backpack, etc. It sucks. It's not sleeping in any real sense and can power up to full power if a fly farts too close to the microphone.
For better or worse (worse IMO), I think that what we knew as "suspend to RAM" or S3 is gone forever. It was apparently just too hard to get working reliably with all the peripheral hardware and they gave up.
Everything I have read says that for any recent laptop, if you want reliable suspending that won't burn battery you have to always "hibernate" or "suspend to disk". It takes longer to start back up but initializes all the peripherals from "off" so it can be more reliable.
I'm still working with my older HP laptop that has legit S3 and am dreading an upgrade to a "modern" one.