[starfallg]

It really depends on the organisation, but from my observation (I, myself, never developed any side projects worth releasing so this is based on what others did), most large organisations are not like that. Legal and HR specifically are very risk averse, so permission is usually denied by default, unless there is a overriding benefit to the company (or someone else to take the hit when things go wrong, a very cynical take I know).

Ethically speaking, I would think that as a principle, employees should never agree to ask the employer for permission to do things in their own time, for their own purposes, outside of the area of the business. Employees are just that, employees, not indentured servants. There are duties owed by employee to employer (and vice-versa) but this should not be one of them.