Everything runs fine until the last step, installing FreePbx. I had to fix an error due to gettext not being enabled in /etc/apache2/php.ini : this should be added to this excellent wiki (thanks to the author).
When I run the ./install -n command, I got several errors due to the database missing elements. I fixed all, and explained here what I did, but since that I found a very similar explanation which ran fine.
This install ran really fine.
There has been only two additional operations to do before running the last command (./install -n)
activate the gettext extension in /etc/php/…/cli/php.ini
Change the Apache2 User and Group in envvvars, it was done only in apache2.conf, which indicates clearly (in 2021) that this should be done in envvars.
I also installed on a SOC similar to the Raspberry Pi (ASUS Tinker Board), and the only additional problem I had is that the odbc driver for mariadb is not present in Debian. Following this post, I was able to build without any trouble :
Note that the path to the obdc driver is not the same as in the process indicated above. In case the link would disappear, here is the part of this post that I used :
# Install MariaDB ODBC Connector
cd /usr/src
git clone https://github.com/MariaDB/mariadb-connector-odbc.git
cd mariadb-connector-odbc
git checkout tags/3.1.1-ga
mkdir build
cd build
cmake ../ -LH -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr/local -DWITH_SSL=OPENSSL\
-DDM_DIR=/usr/lib/arm-linux-gnueabihf -DCMAKE_C_FLAGS_RELEASE:STRING="-w"
cmake --build . --config Release
make install
# Configure ODBC
cat <<EOF > /etc/odbcinst.ini
[MySQL]
Description = ODBC for MySQL (MariaDB)
Driver = /usr/local/lib/libmaodbc.so
FileUsage = 1
EOF
cat <<EOF > /etc/odbc.ini
[MySQL-asteriskcdrdb]
Description = MySQL connection to 'asteriskcdrdb' database
Driver = MySQL
Server = localhost
Database = asteriskcdrdb
Port = 3306
Socket = /var/run/mysqld/mysqld.sock
Option = 3
EOF