https://docs.halium.org/en/latest/porting/first-steps.html <--

sudo apt install git gnupg flex bison gperf build-essential \

zip bzr curl libc6-dev libncurses5-dev:i386 x11proto-core-dev
libx11-dev:i386 libreadline6-dev:i386 libgl1-mesa-glx:i386
libgl1-mesa-dev g++-multilib mingw-w64-i686-dev tofrodos
python-markdown libxml2-utils xsltproc zlib1g-dev:i386 schedtool
repo liblz4-tool bc lzop imagemagick libncurses5 rsync
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'libreadline-dev:i386' instead of 'libreadline6-dev:i386'

E: Unable to locate package repo

IUbuntu 20.04.1 LTS
OS Type 64-bit
Memory 19,5 gb
Processor Intel core i7-4770
graphics gtx 1050 ti 4gb
Disk Capacity 1,6 TB

how to solve?