thats where you need to look at what services are available in your area.
if its just a exchange order market as the only converters. then yes that business would be seen as being an investor of a currency and have to declare such
however if there is a payment processor (no public market orderbook) which offers shopping cart options, where the total price of sale includes the currency conversion commission which the customer pays the extra then that is declared the same way as having a shopify or other merchant tools platform like accepting credit cards. which is not treated as an investment in alternative currency.
EG as a customer when i buy something internationally my receipt/bank statement shows 2 lines. one for the sale and one for the currency conversion. thus the business isnt paying for conversion. but they receive the native fiat they want
many businesses operating internationally that have sites that accept different countries fiat use shopping cart/card processing services. where the exchange to the end recipients native fiat is done on the customer/service side and the end business just gets their native fiat thus avoids all the taxes and duties of international tax stuff.
fiat is fiat. and what becomes important is not the receipt of fiat. but what the service does that sent you that fiat.
in short its very difficult to explain to a tax office that a receipt of fiat from a crypto service is just payment for goods if that service is not a merchant tools service and instead only offers currency swaps/investments.
for instance
many businesses in the US get fiat from coinbase and from bitpay. roughly the same volume each week.. but because it comes from different services its treated differently for tax reasons
EG you personally could get $1k from a relative, $1k from your employer, $1k from a retailer, $1k from government social security, $1k from an exchange and $1k from a merchant tools site
the $1k from relative is treated as 'gift'/personal loan (no tax)
the $1k from employer is treated as 'income' (income taxed)
the $1k from retailer is treated as 'refund' (untaxed)
the $1k from social security is treated as 'social benefits' (untaxed)
the $1k from exchange is treated as 'investment' (capital gains taxed)
the $1k from merchant tools is treated as 'business sales income' (sales/vat taxed)
where they all have totally different tax categories, even when its the same value being received