First, to confirm what others have said, it works just fine without any cell connection, so you don't need that feature.
However ...
When I got my iPad Mini 5 I opted to pay the $150 to get the cell capability. Why? Well, for one, I do not own a cell phone and have no plans to get one, but I figured that this might let me use the iPad to make emergency phone calls from my car, if needed.
But that is only the tip of the iceberg. Getting the cell service version turned out to be a REALLY GOOD IDEA for many other reasons. Read on ...
1. While you actually cannot use the iPad as a phone (meaning that you can't add it to a cell phone plan, and it cannot use the cell phone network), you can get a data plan and make phone calls via the data network (see below).
2. You can purchase data REALLY CHEAP. I shopped around and got a 5 GB plan through T-Mobile that is good for four months. It only cost $30, which is less than $10/month. When this expires in October, I can switch to whatever carrier has the best plan at that point. There are no contracts and the Apple SIM card works with pretty much all of the carriers.
3. I already have a voice over IP (VOIP) phone number that I use through my home PBX. You can get this for free via Google Voice, or you can pay $30/year to get a service that not only gives you a dedicated phone number, but also gives you voicemail and even the ability to receive incoming faxes (which I've actually used once or twice).
4. You can then download an app that lets you use this VOIP phone number on your iPad. When someone calls that number both my home phone AND my iPad ring. Whichever picks up the call first gets the call and the other is locked out. What this means is that I can answer my home "line 2" (line 1 is still a traditional landline) from anywhere in the world. I can make free calls anywhere in the USA from the iPad.
5. While in my car, I can use my iPad to listen to any music service (very little data used); use Google maps; and do all the other things that those of you with smartphones now take for granted.
6. Since you can't connect to the phone network, you cannot do SMS text messaging. However, you can text message to anyone with an iPhone using iMessage. Most people now use this instead of SMS because it has no text limit and you can attach pictures.
So, that one-time $150 to get the cell feature added to the iPad can give you lots of features.
Oh yes, for flying with your Mavic, having the cell service does give you one thing you don't get without it: maps. You can pre-download these while you're still on Wi-Fi, but if you are out in the field and have forgotten to download the maps ahead of time, and if you need them (I don't), then with the cell service they will be instantly available.