Here is a modified version of @Ken's extension "YourFont". YourFont doesn't work with Companion (on devices with Android > 9) since the AI2 nb184 release.
Update v1.2, June 8, 2021
Recompiled version to avoid that a service is removed from the Manifest with another extension (so better use this):
EDIT: de.bodymindpower.MyFonts.aix (aix removed)
Details on this issue can be found here.
Update v3, March 11, 2022
Here is a new version that does not add READ permission to the Manifest.
If you use this version the fonts must be stored in the assets. MyFonts_3.aix (5.9 KB)
The path to the assets for devices with Android < 10 has changed (since the nb187 release) from: /storage/emulated/0/AppInventor/assets/
to: /storage/emulated/0/Android/data/edu.mit.appinventor.aicompanion3/files/AppInventor/assets/
Therefore, the extension no longer worked under Android <10 with Companion. Here is the update that fixes this problem: MyFonts.aix (5.8 KB)
Thank you so much you are too good I was thinking that I have to compromise with it but you have done the work for me thanks a lot it really means a lot.