Nioh and Nioh 2 (including all DLCs) are also bundled in the Nioh Collection on PS5.
A very quick and easy way to farm and earn Amrita and Gold fairly early on is by doing the Sub Mission Finders Keepers. It has a Mission Level of 15 and is given by Kuroda Nagamasa. It requires you to retrieve his famed sword Heshi-Kiri-Hasebe from a cave beneath the mountain of Nakatsu inhabited by Yokai.
Aside from that and much early on, you can also do the Main Mission Isle of Demons again and farm the 3 Yokai that spawn in the room to the right of the Shrine near the Hotspring. It has a Mission Level of 7.
For farming Gold early on, you can try to complete the Sub Mission Guardian of the Underworld against waves of enemies. It has Mission Level of 25.
In terms of farming gold, you may be tempted to sell them off directly at the Blacksmith, though there is a way to earn more gold from this.
Easy Amrita and Gold Farming
Method 1 – Sub Mission Finders Keepers
The Mission is actually very quick. You just need to defeat the Yokai that is carrying the sword of Kuroda Nagamasa. Of particular interest are the Yokai found in the area that have golden crystals on their backs. They typically run away, exposing their back. Farm them and you will get a good amount of Amrita after the mission. The enemies also occasionally drop loot which you can sell or offer at the shrine.
In addition to the gold rewards after the Sub Mission, you will receive Ikkoku Nagayoshi Spear (Earth), The Raging Bull: Kabuto, The Raging Bull: Do and The Raging Bull: Hizayoroi. All of these you can sell or offer at the Shrine as well.
For around 5 rotations of the Sub Mission (which may take 10 minutes or less), you should be able to obtain somewhere around 49,000 Amrita (including Shrine offerings) and 40,000 Gold (including selling at the Blacksmith).
Method 2 – Main Mission Isle of Demons
To use this method, you must have beaten Onryoki (the boss of the Mission) already. After you do, proceed to the Shrine near the Hotspring and pray, then go to the room to the right. There will be 3 Yokai there that you can kill for a total of somewhere around 1,100 Amrita in one minute. Then head back to the Shrine to allow them to respawn and repeat. In an hour, you should be able to get around 120,000 Amrita.
Method 3 – Sub Mission The Guardian of the Underworld
To farm gold, you can try to complete the Sub Mission The Guardian of the Underworld, which can be accomplished in less than 3 minutes if you remember where the enemies spawn. One rotation yields around 13,700 Gold. You will also gather a good amount of Amrita in this Sub Mission.