Softr & Stripe - adding VAT number in checkout

Hello guys, I ran into the problem with Softr+Stripe checkout. I need my customers to be able to add VAT number (if they need it in the invoice) in the checkout page. And you can’t add the VAT after the purchase since invoice isn’t editable after creation in Stripe.
VAT and custom fields can be added in Stripe Checkout Links but in that case you lose access to the automatic user subscription enrollment between Softr and Stripe. It can be done via automations - Zapier + Data Fetcher + the Stripe Checkout Links, but that’s like a long hard (and also paid - two more services) workaround.
Does anyone has any other solutions? Have someone dealt with that, especially EU Softr business owners?
Thank you!