<TL;DR> - Eufy cameras use either wifi or need a homebase. Some take SD takes, other use the HomeBase storage.  Some can work with HomeKit.  They are good cameras for the price. I haven't tried their outdoor cameras (I have a full PoE system and Eury do not support PoE)  </TL;DR>

So, just to clarify - there are two different types of Eufy cameras:

* Those that require a HomeBase (which comes in 2 different versions), for example all the external cameras and the Eufy Doorbell camera
* Those that work over Wifi (Security light camera and indoor cameras)

Generally (and don't quote me 100% on this as Eufy are great at changing their minds):

* Wifi cameras have their own local storage such as SD Cards.  The 2 indoor cameras (2K Indoor and 2K Indoor pan-and-scan) are also both HomeKit compatible (with a bit of work, but they do work and also support HKSV, which allows for face recognition and notifications via HomePods, etc.)

* Security Light cameras take SD cards

* All external cameras require a HomeBase.  HomeBase 1 has SD Card, HomeBase 2 has 16GB build in storage (plus there are other differences)

* Doorbell camera requires a HomeBase (or do what I did and buy it in a pack with the HomeBase 2).  This then acts as the 'ringer' unit for the doorbell

* Indoor cameras require power (USB adapter included)

* Outdoor cameras have batteries (obviously the security light camera requires 240v)

Now, as an Apple user, Eufy are REALLY annoying - they have promised HomeKit video on many of their devices, including HomeBases, but often this never happens.  Read their forums for more info.   But HomeBridge can fix this to a certain extent.