There is a flavour of Debian which has preinstalled all fonts which are recommended for every supported language desktop version. It is the live system on the installation media. When you run your Debian from a USB flash drive, it has all the fonts ready because it has configured all supported localisations for desktop. On Debian, you can replicate this by installing
live-task-localisation-desktop package. The package is not explicitly intended for non-live installation. According to its description:
This metapackage installs packages and documentation to help support
Debian live graphical desktop environments for other languages.
Michael Biebl reported that if you install Debian using the live installation media for GNOME, all localisation tasks are installed. I also had a similar issue and had it resolved by removing some live packages. It was more than a year ago, but it should still be true for the current 10.5 release. You can use it to your benefit, but it can be considered a bug because it is safe to assume that a regular user will not need localisation for languages that such user has no command of and did not intentionally install. It also may cause inconvenience by cluttering the system.
For example, the fonts will be displayed as options in LibreOffice
despite them being unused.
Fonts take up disk space. It may be an issue for some users.
Localisation also installs spellchecking support for those languages,
which leads to further clutter, like too many dictionary options
in Firefox and Thunderbird.
Localisation also installs other packages, not all of which are necessary for displaying fonts, such as Debian reference translations.
A solution to the last two could be a metapackage depending on recommended fonts only. At the moment there seems to be no such package. It would be nice to have one, so that all language-specific fonts show up correctly at all Wikipedia pages, for example.
You can preview the list of packages, which would be installed if you installed
live-task-localisation-desktop like this:
$ sudo apt install live-task-localisation-desktop --assume-no
The fonts packages are grouped together and their names start with
fonts-, so you can just copy them all together and install manually in one run if you wish.
If copied from terminal, you will need to remove new line characters
\n first. You can do it in
gedit or a different text editor by running find and replace of
\n for an empty string.
The list of packages also contains fonts starting with
xfonts-, but they are bitmap fonts which are mostly intended for use in terminal, so you do not need them for web.