I realize I didn't really take the time to explain my point, so here are more info :
One of my machines runs with a Ryzen 2400G, which in a way is really similar to a 2700U. The graphics part now runs flawlessly but I had to move to a bleeding edge recent version of everything.
I struggled a lot to make things work using backports and all but then I realized I had to tweak almost everything related to graphics. I decided to move to Debian sid, which an unstable release, and everything worked out of the box, since it has really up to date versions of everything.
The nomodeset is a trick to fallback to default video mode and you won't be able to use the iGPU of your system with this. So it will only be a temporary workarround which could help us getting our hands on log files and tell you what's exactly going on. But from my experience, what's going on is that your hardware is not properly supported by the version of your kernel and everything arround it.
You should also update your bios if you can still boot on Windows. I've seen some people telling that some bios for ryzen laptops are broken.
Take a look at this if you dare :
https://bugzilla.kernel.org/show_bug.cgi?id=200087