一、Seems I once answered a similar question.
二、In my opinion, 一点(儿) is similar to “a small/little quantity of sth”. So according to the use of 'quantity', we can put 'coutable' and 'uncountable' nouns after 一点(儿)。Normally, we put a coutable noun which is relatively small in figure/size and uncountable nouns after 一点儿。
For example:
我昨天买了一点儿花生。I bought a small quantify of peanuts.
我中午吃了一点儿牛肉。I ate a smalle quantity of beef.
三、In the above examples, we can (**but not always can**) put countable and uncountable nouns after "一点儿". As stated before, if a countable noun is put after '一点儿', it should be relatively small in figure/size and its quantity/数量 can't be counted/known at first sight.
1). For example, 花生/peanut, 种子/seed, 豆子/beans, 葵花籽/sunflower seeds etc.
2). If the size is not so small, but the overall quantity is still small to me, I would also use 一点儿. For example,'我昨天买了(一)点儿苹果'. Sometimes 一 is omitted.
3). Seems, we normally don't use '一点儿' to modify relative larger animals, like cats, dogs. The reason may be that normally we only have one or two cats. It can be a habit, not language.