There are lots of different versions of biscuits that are basically ground almonds (or other nuts), egg whites & sugar. I would use macaroon as a generic name.
Macarons are the French ones that are pretty coloured & sandwiched together with jam. I haven’t tried making these as my recipe includes grinding pistachio nuts - that’s probably why they are quite expensive. There are also the Italian amaretti biscuits that can be hard or soft (again not tried baking those).
The ones I have tried baking are a bit humbler (but can be made in large quantities) & are:
Zimtsterne are a type of German Christmas biscuits - I think there are other similar types of German Christmas biscuits in the same style. I started to make these as my favourite gingerbread recipe uses egg yolks so I wanted a recipe to use up the whites. These are quite easy (although I do have a large mixer to do the hard work of beating the egg whites) & the dough stood up to be rolled & cut out by DC.
The easiest ones I have made are Nigella’s Spanish macaroons that you just roll in rough balls - I’m not too keen on these but DS2 devours them.
My current favourite is Nigella’s Ricciarelli, which are fairly easy diamond shaped biscuits - these seem to be quite fashionable to sell in small bags at present as I’ve seen them in bakers & M&S, so it is quite satisfying to make a large batch.
Both the last 2 are quite forgiving for using substitute flavourings (eg marmalade if you want to bake at short notice & have no oranges). I tend to miss out the almond essence in all these recipes as I find it a bit overpowering.
All macaroons take a bit of getting used to compared to normal biscuits as the texture is different, but ground almonds are definitely your friend in baking gluten free if (like me) you are not an expert.
I also wondered about buying or even making ice lollies from fruit juice rather than a sorbet - I have vague memories of an Annabel Karmel recipe where she used different types of juice in a mould so you got different colour layers.