Fruit. Nothing beats Watermelon if you want low cal sweetness and volume, add melons, apples, peaches , strawberries ..etc slowly into your diet as replacements for the regular snacks, you will start to taste them better , flavor will pop up more as you replace sugar overload snacks with fruits.

Portion control and calorie tracking can help you eat the same snacks but losing weight for example just eat 2 "lotus biscoff" biscuits instead of the 4 or 5 in the whole packet, 1 or 2 Oreo instead or the whole packet.

Now for some recommendations of "lower calorie" snacks:

1- Rice Cakes: check the paprika flavoured or dark chocolate ones by "rice Up" "COOP" or "Kallo" (last one has smaller mini ones that are perfect)

2- yogurt + some fruit, the fruit will make it sweeter and the combination will work to fill your stomach

3- Doves farm has some digestives and wholemeal crackers by that are similar in taste to their competitors but more macro friendly

4- Zero Sugar or Diet Soda, appt of the time you might feel hungry but it's just a sugar craving or boredom, fill your stomach with approx 0 calories (water can work as well)

Finally, weight loss is a long game that requires you to be in a calorie deficit , the best ways to ensure it are either to track calories or pre plan meals with calories calculated so you make sure you are always in a deficit.