お土産を探しているのですがって英語でなんて言うの？

Any of these phrases will suffice.

"Where are the souvenirs?" Asks them to tell you where in the shop the souvenirs are. "Do you sell souvenirs?" Asks them if they sell any souvenirs. "I am looking for souvenirs." Tells them that you are looking for them and will allow them to tell you where you can find them.

You may also need to specify what you are looking for. You can use adjectives to describe what you want so that the shop staff will be able to understand what you are looking for.

Some shops do have specific areas where products that are ideal as souvenirs are displayed. The area or shelf where such items are displayed may not be easily found by a customer. So, you would have to politely ask one of the shop staff to direct you to the area or shelf where you can find items that are ideal as souvenirs. So, you may say: I would like to buy a souvenir. Please show me the area where I can find the ideal items. or Please direct me to where souvenirs are are. I would like to buy one.

When on holiday and if you wish to purchase a gift for a loved one you may say: "I would like a souvenir." "I am looking for a souvenir." "I would like to purchase a souvenir."

You can use any of the sentences above in both formal and informal conversation. In all three sentences, you are expressing what you need and then you are asking if they can help you attain it. "Do you have...?" "Can I buy it here?"

A common way to say this in British English is ' I am souvenir shopping'. We would often say 'Shall we go souvenir shopping today?'. You could also be more specific and say that you are looking for something for a friend. This is implied when you say you are looking for a souvenir but it gives you the chance to go into more detail.

There are other words you can use in place of 'souvenir' when looking to buy a souvenir in a shop. Two of the most suitable alternatives are: 'memento' and 'keepsake'. Memento is a straightforward alternative word for souvenir. Keepsake is often used for a small item kept in memory of the person originally owned it or who gave it but it is also often used in place of souvenir. e.g. I always buy myself a keepsake to bring back home when on holiday.

It depends on the situation, but you can use one of these phrases.

If you are in a store and someone comes up to you and you would like to tell them you are looking for souvenirs, you can simply say something like "Hello there, could you help me? I am looking for some souvenirs.". This is a very polite way of telling someone this.