I've read very positive reports on the Farad Super 3 which is a double regulated super capacitor linear power supply (LPS), and the 19V version is recommended with the Nucleus.
https://faradpowersupplies.com/shop/en/home/51-15279-super3-power-supply.html
https://faradpowersupplies.com/shop/en/home/51-15279-super3-power-supply.html