Check option 5 from this guide and how to use the umbrel onchain wallet into another app.
But I do not recommend to use it as a normal wallet!
YOU HAVE BEEN WARNED!
Due to the “anchor reserve” feature in LND, some UTXOs will be linked to your LN channels, and will not be usable. You can really fucked up your channels using those UTXOs.
As to have it just in case of SHTF, yes, you can use it in Sparrow (Bluewallet, Zap, Blixt) but do not use it in the same time in Umbrel.