How do you process user payments - excluding

if you really really want to use Stripe, you can by forming an llc in the US: https://usamaejaz.com/using-stripe-pakistan/

Just use your bank's virtual POS solution or a similar local service which works with your bank.
We use Braintree but I think this is the same as PayPal.

Highly dependent on the context of the business, what are you working on?

One option I have used in the past was Skrill
Bitcoin and other crypto might also be an option

You could also use a 3rd party like Gumroad, Clickbank or 2Checkout

This Shopify page will give you some help based on country, but they don't list every possible service.
https://www.shopify.com/payment-gateways/poland

A lot will depend on country, product and business model.

Payment options may limit what kind of business you can run.

You also have the option to found a company in another country e.g. Estonia or use Stripe to found a company in the US.