I'm trying to install libasound2-dev on a freshly installed Ubuntu 20.04 on my Raspberry Pi 4 but apt reports that it can't find the package.
Running apt search libasound2 yields:
ubuntu@ubuntu:~$ sudo apt search libasound2
Sorting... Done
Full Text Search... Done
alsa-topology-conf/now 1.2.2-1 all [installed,local]
ALSA topology configuration files
libasound2/now 1.2.2-2.1 arm64 [installed,local]
shared library for ALSA applications
libasound2-data/now 1.2.2-2.1 all [installed,local]
Configuration files and profiles for ALSA drivers
ubuntu@ubuntu:~$
Looking at the package repository however, it should be available for arm64: https://packages.ubuntu.com/focal/libasound2-dev
My /etc/apt/sources.list is below (after removing commented lines).
deb http://ports.ubuntu.com/ubuntu-ports focal main restricted
deb http://ports.ubuntu.com/ubuntu-ports focal-updates main restricted
deb http://ports.ubuntu.com/ubuntu-ports focal universe
deb http://ports.ubuntu.com/ubuntu-ports focal-updates universe
deb http://ports.ubuntu.com/ubuntu-ports focal multiverse
deb http://ports.ubuntu.com/ubuntu-ports focal-updates multiverse
deb http://ports.ubuntu.com/ubuntu-ports focal-backports main restricted universe multiverse
deb http://ports.ubuntu.com/ubuntu-ports focal-security main restricted
deb http://ports.ubuntu.com/ubuntu-ports focal-security universe
deb http://ports.ubuntu.com/ubuntu-ports focal-security multiverse
If it helps, it seems like this problem isn't specific to libasound2-dev. It seems that apt can't find anything in the libdevel section.