Rumor: Sony is indeed developing a real portable console
According to insider Moore’s Law is Dead, the console will be based on a custom APU from AMD (like most modern portables, including Steam Deck and ASUS ROG Ally) and will be able to run games from PS4 and even from PS5, but in the latter case – at a much lower resolution than the original.
The console is in the early stages of development and will not be released earlier than in 2 years.