How to allow Chromium (snap installed) to use /tmp as the download folder

The answer is here: https://askubuntu.com/a/1264341 with a copy and paste version:

mkdir /home/you/tmp
sudo mount --bind /tmp /home/you/tmp/

Just force to set Chromium’s download folder to the /home/you/tmp

To make it permanent you can add this line to the /etc/fstab:

 # <file system> <mount point>   <type>  <options>       <dump>  <pass>
/tmp        /home/you/tmp   auto    bind    0   3

and rebuild the initrd with sudo update-initramfs -u -k all.