You can purchase apps and digital content on Google Play / Apple Store / Huawei AppGallery using payment methods from your Google / Apple / Huawei account.
You can read more about the accepted payment methods on the following webpages:
Google Play: https://support.google.com/googleplay/answer/2651410?hl=en&ref_topic=3365267
Apple Store: https://support.apple.com/en-us/HT202631
Huawei AppGallery: https://consumer.huawei.com/sg/support/content/en-us00698199/