The NaOH you describe is fine to use in soap. That is about the same as what I use, and it works well.
For the record, you CANNOT have 100% pure NaOH. Even reagent grade NaOH has some tiny level of impurities. Anyone who tells you otherwise is misrepresenting their product. Or they are trying to say, as we discussed earlier in this thread, that there are no additives specifically and intentionally mixed into the NaOH. There's a difference between impurities naturally present in any chemical versus additives.
A sack of beans can be 100% beans in the sense that additives such as rice or barley have not been intentionally added to the beans. But that sack of 100% beans will always have a small amount of impurities -- stones, sticks, etc. -- that are naturally present due to the beans being an agricultural product.
A container of NaOH can be 100% NaOH in the sense that nothing else has been added to the NaOH. But it will always contain some level of impurities -- sodium carbonate (carbonate sodico), trace metals, water, etc. -- that are naturally found in NaOH due to how chemically reactive it is, the particular process by which the NaOH is made, and the raw materials used to make it.