I have a Steam Deck and I don't even own a PS5, so I'm probably way outside of the market for the Portal...
But I'm really finding it hard imagine this device finding a broad audience, since even in a hypothetical best case we're talking about a subset of a subset of PS5 owners. From what I understand the new PSVR sold pretty badly despite being a pretty solid piece of VR hardware, this feels like a very niche and underwhelming piece of hardware and so I really can't imagine it performing any better.
Someone will buy a PS Portal, and hopefully they like it, but when the smoke clears I don't see it being a big hit.
The Steam Deck OLED on the other hand, I suspect will sell out fast. It seems like there is a pretty big chunk of people who were interested in the first gen Steam Deck but opted for the wait and see approach, and I can imagine a lot of those people jumping on the Steam Deck OLED now that they know the device has lasting power. Personally I probably can't justify the cost of upgrading from the LCD model right now, but I'd be lying if I said I didn't want to...