V-mic mini from Saramonic
The V-mic mini is a shotgun microphone, which means that it records audio with a tight, focused polar pattern and makes it a great choice for dialogue. Speak directly into the microphone, and you will have a well-balanced, rich sound. Furthermore, because of the microphone's construction, it cancels unwanted frequencies and noise that come into both sides of the microphone. This is because it has a unique, tube-like design that removes noise from the sides.
You can mount the V-mic mini on your iPhone or Android phone, and it works with both. If your phone supports a 3,5 mm stereo mini-jack, you just plug it in. If you have an iPhone with a Lightning connector or an Android with a USB-C connector, you need to use an adaptor, but other than that, it's just plug-and-play. You don't need power, and you don't need an app. It's a great little mic, and you will get great sound from a shotgun mic like this.
Blink 500 from Saramonic
The wireless option is the Blink 500 set. Blink comes in three different versions. You can get the dual-box, so you get two mics — or you can get the single one if you don't need two mics. Both options work with Android and iPhone. The receiver can use two channels — so if you start by picking up the single pack and later figure out that you want a second microphone, you can just get another. You don't need to buy a completely different set. The other good thing about this Blink 500 set is that the transmitter has a built-in microphone. If you don't want to use the transmitter as a mic — you can also use the lavaliere mic included in the box.