Hi,
You can try ajax.loadAsset method and pass the template inside it.
var core = require( 'web.core' );
var ajax = require( 'web.ajax' );
var Dialog = require( ' web.Dialog' );
var qweb = core.qweb;
var rpc = require( "web.rpc" );
var _t = core._t;
var session = require( 'web.session' );
const {assets} = require ( '@web/core/assets' );
// Load the XML templates
ajax.loadAsset('vendor_portal_validation', 'xml', '/vendor_portal_validation/static/src/xml/vendor_portal.xml', { }, qweb).then(function () {
// Templates loaded, you can now use them
var renderedTemplate = qweb.render('vendor_portal_validation.template_name', { /* template variables */ });
// Use the rendered template as needed
});
});

Hope it helps