Followed instructions from @cormullion posted here and all steps below could be performed alright.
However, no signs of JuliaMono fonts after creating the local.conf file, restarting UserLand, Debian linux and Julia 1.6.1:
cd /usr/share/fonts/truetype/
wget https://github.com/cormullion/juliamono/raw/master/juliamono-ttf.zip
sudo apt install unzip
unzip juliamono-ttf.zip
rm -r juliamono-ttf.zip
sudo apt install font-manager
$ fc-cache -f -v
sudo apt install nano
nano /etc/fonts/local.conf
# create file with content:
<alias>
<family>monospace</family>
<prefer>
<family>JuliaMono</family>
</prefer>
</alias>