There is an example of describing intent filters in json here. The relevant section of the manifest is intent_filters
{
"manifest_package": "org.chromium.webapk.test",
"scope_url": "https://pwa.rocks/",
"intent_filters": {
"scope_url_scheme": "https",
"scope_url_host": "pwa.rocks",
"scope_url_path": "https://stackoverflow.com/"
},
"start_url": "https://pwa.rocks/",
"display_mode": "standalone",
"orientation": "portrait",
"theme_color": "2147483648L",
"background_color": "2147483648L",
"icon_urls_and_icon_murmur2_hashes": "http://www.pwa.rocks/icon1.png 0 http://www.pwa.rocks/icon2.png 0",
"web_manifest_url": "https://pwa.rocks/pwa.webmanifest",
"version_code": "1",
"version_name": "1.0",
"bound_webapk": {
"runtime_host": "org.chromium.chrome",
"runtime_host_application_name": "Chromium"
}
}