To use the DIN 5008 document layout for non-German companies, it is sufficient to simply install the German accounting package (l10n_de). This package simply does not need to be activated in the financial configuration and therefore does not affect the chart of accounts, tax rates, etc.

EDIT with additional info:

The german accounting can be installed through the apps. Make sure to remove the existing filter when searching for l10_de.

The DIN5008 layout can be activated through the general settings under "Configure Document Layout". Minor changes to the layout can be made through this window or using the Studio app.