Shopify Pyament Gateway Question

Hello everyone, I'm new to this forum, sorry if I'm posting in the wrong section but I have a very important question (might be dumb for some) but anyways, does running a store with only PayPal as a payment gateway, would that ruin the conversions or is it normal, and can it actually work?

No, it's normal.

I know a lot of Shopify sellers from my country using only PayPal and making decent money.

No it won't ruin the conversions. Generally the more payment methods you offer, the better your conversion rate will be.

If you have a high abandoned checkout rate, you can reduce this by clearly advertising what payment methods are available PRIOR to the checkout page.