There is Branch io support answer:
Thank you for contacting Branch Support.
Branch links will open the default app store on the device. On devices
where Huawei App Gallery is the default app store it will be opened to
download the app.
If you want to try opening the Huwaei app market even when there is a
different default app store, you can try entering the App link in the
format https://appmarket://details?id=com.xx.xx
Once the app is installed there is no change in the functionality due
to the source of app install.
UPD 08.02.2021 second answer:
They are two methods on how to use a single link which works on both
Google Play Store and Huawei App Gallery
Method 1 -
Set the Custom URL to point to your app on the Huawei App Gallery, on
the Configuration page. And set the $android_url parameter for all
links to the app on Google Play Store.
In this case on Huawei devices the link will redirect the users to the
Huawei App Gallery when the app is not installed. And on other Android
devices as the link will not be available, the fallback url set by
$android_url will kick in, opening the Google Play Store.
Method 2 -
Choose your app from the Google Play Store on the Configuration page.
If you have any specific links targeting Huawei users, then change the
Default Redirect for those links to the Web URL of your app on the
Huawei App Gallery.
Do let me know if this helps.
UPD 09.02.2021
On the link kindly use the Default Redirect for Android as well.
The default in this case would be the Huawei App Gallery link to your
app.
On the link data page can you add key - $fallback_url
value - The play store link to your app
After making the changes on the link, please test the link on both
Android and Huawei devices at least after an hour or two as the link
level changes sometimes take a while to reflect.
UPD 07.04.2021
We had another round of discussion with the Product team on this
issue, and they mentioned that the fallback to Huawei app gallery is
not supported anymore.
They have not provided us with the exact details, but they seem to
have been changes on the OS level on Huawei devices which has broken
the functionality and which we have been unable to fix due to certain
limitations.
Unfortunately this flow is not supported at the moment.
I do apologise for any impact this might have on your link, but it
does look like we do not have any solutions for this matter at the
moment.