The Netherlands have held onto their dialects, which are similar to the Low German dialects that were once present within German borders. These dialects are not understandable to speakers of High, Middle, and Upper German. Though familiarity with Low German dialects may be beneficial, it should be noted that German dialects spoken in Germany are also not universally comprehensible.
The nomenclature for Germans and Germanic tribes is somewhat convoluted. During the Middle Ages, the term “Dutch” was derived from Low German and used to refer to all inhabitants of what is now Northern Germany, Flanders, and the Netherlands. Over time, with changing national identities, “Dutch” became associated specifically with the language spoken in the Netherlands and the people who reside there. Meanwhile, in Britain, the word “Holland” became a colloquialism for the country.
The situation is chaotic. However, if you examine the terms for German in French, Russian, and Finnish, you will discover that other languages also struggle to name the German people.
Keep in mind that language is a tool for communication. Therefore, it is acceptable to use “I’m from the Netherlands” instead of “I’m Dutch” if it makes you more easily understood.
The term “Netherlandish” can be used as an adjective, although “Dutch” is the more commonly used term. However, if using “Netherlandish” can help you avoid repeatedly clarifying that you are from the Netherlands and not Germany, it is acceptable.
In a CV:
You’re simply indicating the country of your citizenship, and not referring to your national identity. Similar to how I would state “United Kingdom” instead of English or British.