For those wanting to go beyond hobbyist, talking to a company of your aligned interests in their product often magically provides you with their SDK or facilities. With the dispersed world wide development these days, that can add some complication to this formula.
Just the other day we had several stories about a new interesting operating system DBOS that was closed source proprietary for profit.
This also seems to be closed source proprietary for profit.
Nothing inherently wrong with it, but I wish i could play with them at home. Opens sourced operating systems seem t obe losing ground.