How to let users add an attachment to a SendGrid form (Wix velo code, javascript)?

I see plenty of answers around the internet, including the Wix community forum:

https://forum.wixstudio.com/t/file-attachment-using-sendgrid-api/34156

BUT they require a .js setup, while I already have a .jsw setup.

Do I really have to build a completely new backend? Can’t I make this work with the .jsw code I already have?

My backend:

// backend/sendEmail.jsw

import sgMail from '@sendgrid/mail';
import wixSecretsBackend from 'wix-secrets-backend';

export async function sendEmail({ to, subject, text, replyto, fromname }) {
    try {
        const sendGridSecret = JSON.parse(await wixSecretsBackend.getSecret('sendGridSecret'));
        const key = sendGridSecret.key;
        const senderEmail = sendGridSecret.senderEmail;

        sgMail.setApiKey(key);

        const msg = {
            from: {
                email: senderEmail,
                name: fromname // Use the provided sender name (wix current user)
            },
            replyTo: replyto, // Use the provided reply-to address
            to: to,
            subject: subject,
            text: text
        };

        const result = await sgMail.send(msg);

        console.log('Email Result:', result);

        return result;
    } catch (error) {
        console.error('Error sending the email:', error.response?.body || error.message);
        throw error; // Rethrow the error to propagate it to the caller
    }
}

.

My frontend:

(...)

if (urlId) {
        const projectEmail = await getProjectEmail(urlId);
        const projectTitle = await getProjectTitle(urlId);

        if (projectEmail && projectTitle) {
            $w('#sendButton').onClick(async () => {
                const passedValidations = checkFormFields();

                if (passedValidations) {
                    try {
                        displayMessage('Sender...');

                        const emailResult = await sendEmail({
                            to: projectEmail,
                            subject: $w('#subject').value,
                            text: "*** nDenne besked er sendt fra en profil på kreativthold.dk, til '" + projectTitle + "'. nOBS: Nogle vedhæfter en fil, tjek selv. nDu kan svare personen direkte, ved at svare på denne mail. n*** nn" + $w('#emailContent').value,
                            replyto: $w('#replyToMail').value,
                            fromname: $w('#fromName').value
                        });

                        if (emailResult && emailResult[0]?.statusCode === SUCCESS_CODE) {
                            clearFields();
                            displayMessage('Din mail er sendt!'); // Success message
                        } else {
                            displayMessage('Noget gik galt, kontakt support.'); //sendGrid fejl?
                        }
                    } catch (error) {
                        displayMessage('Kunne ikke sende mail, tjek felter.');
                    }
                } else {
                    displayMessage('Fejl, tjek at alle felter er udfyldt.');
                }
            });

        } else {
            // Handle the case where the user is not found
            console.error('User not found.');
        }
    } else {
        // Handle the case where the userID is not present in the URL
        console.error('UserID not found in the URL.');
    }
});

(...)

Is it really not possible to add the SendGrid attachment code when my backend is a .jsw instead of a .js ?

I’m scared of messing up my code, tbh..

Lots of thanks in advance