@marcoarment You mention you’re looking at getting a UDM-SE. I feel your pain on deciding what to do..
I also use an UDM-SE, My set up is as follows in the screenshots
I currently use homebridge (docker) which makes them HomeKit Secure video too! (Note that to handle the HKSV I use a Mac mini to do the Processing, a PI is too underpowered).
The benefits are…
Local HDD in the UDM, cloud back up via HKSV to iCloud. Most of my family just uses the home app so it makes it seamless.