GRUB2 font too small on HiDPI screens

[carniz]

Describe the bug
The GRUB2 stage of the installer doesn't handle HiDPI screens that well since the text becomes almost impossible to read.

To Reproduce

1. Boot the installer on a system with a HiDPI (4K+) screen

Expected behavior
One is able to read the text without a magnifying glass

Screenshots

Additional context
elementaryos-6.0-daily.20210430 on a Dell Precision 5510 with a 4K (3840x2160) monitor

[carniz]

Besides making the Grub menu unreadable, the set gfxmode=auto setting in /boot/grub/grub.conf also blocked me from getting anywhere with elementaryOS 6 for a year or so (including trying the early builds). I thus think I can say that this is more than just a cosmetic issue, since it effectively blocked the installer from booting on my system.