It cannot be both of these things at once.
Do you mean that you want to create a virtual pet that isn't part of the Tamagotchi brand?
For the creation of a physical product: With millions of dollars* for licensing, research and development, wages for designers/engineers/programmers/marketing/lawyers/etc., suitable business premises and equipment, tooling, electronic parts, raw materials, and also for complying with relevant global laws relating both to the standards of the factories used and the treatment of their workers and the procurement of materials (for an electronic product you will need to ensure that you are vetting your supply-chain for conflict-minerals, for example), as well as for toy safety testing for every country where you want to sell the product. That's just quickly and roughly off of the top of my head, and it definitely doesn't even come close to everything.
*Electronic parts are usually sold in US dollars, and you will most likely need to deal in this currency for all business dealings relating to this concept.
For the creation of a one-off physical project: You might want to find out if any pre-existing kits from a company like
Adafruit Industries can be adapted for your purposes, and you will need to be able to invest the time to both make and program the device - and to learn how.
For the creation of a computer program for personal use: Depending on what you want to achieve, you may be able to use a drag-and-drop game-creation program to create this, or you may have to invest the time to learn a programming language so that you can have finer control over your project.
