Any idea how the Halo Strix would compare to the base ps5? I assume next round of portables would be Strix based.

Linux is Unix based, just like FreeBSD, which PS3, PS4 and PS5 OS are based on.

So if Sony and Valve want Steam on PS6, they will make Proton (or something similar) for PS6 OS.

As I said, it's not matter of if they can, but if Sony wants Steam on PS6.

It seems it's around desktop 4060, which is faster than PS5, but that's at high wattage (think 70W+).
Some of the portables in the next round are indeed Strix based, like TDP Win 5 and AYANEO Next2, which is quite frankly insane, since that is not APU made for handhelds, but instead for laptops-laptop/tablet hybrids.

Pretty certain Sony's handheld won't be using that, since not only it's big, not power efficient for handhelds, but in addition it's based on RDNA 3.5, and it's reasonable to presume that Sony's handheld will have UDNA architecture, like PS6.

Again, not so simple, PlayStation's OS being based on FreeBSD means nothing, since it was never capable of running FreeBSD programs, let alone Linux programs. It's like expecting the desktop client of Steam to just work on Android since Android is Linux.

How simple, or not, actually it is, I don't know. But is it possible? Absolutely, and it all just boils down to business and not technical decision.

Cerny and AMD's Jack Huynh discuss Project Amethyst, Sony/AMD's collaboration for next gen graphics, which Cerny says is coming in "a few years time"

https://www.vgchartz.com/article/465952/playstations-mark-cerny-and-amds-jack-huynh-discuss-the-future-of-play/

Meanwhile leaker Kepler2, known for his accurate AMD leaks, says PS6 is planned to release in 2027

https://thegamepost.com/playstation-6-release-2027-sony-amd-project-amethyst/

Add a popcorn maker on the side so you can enjoy their movies better/s
But the honest answer is probably more powerful hardware, it's basically their bread and butter.

2027 seems too early for a PS6. During the later years of PS4 I coul already tell the system had peaked and we needed some hardware upgrades ASAP because of the big number of games with mixed resolution and 30 FPS

Simply not really the case now. There are plenty of games still coming to PS4 next year, and only this year PS5 userbase grew bigger than PS4 userbase: https://www.videogameschronicle.com/news/sony-confirms-ps5-has-more-monthly-players-than-ps4-for-the-first-time/

Yeah with the crossgen period lasting so long and big games taking ages to make these days, it kinda still feels like PS5/Xbox Series just came out recently, boggles my mind a bit to realize it's been almost 5 years.

We may see some games release across PS4, PS5, and PS6 which is crazy to think about.

30fps was the norm throughout the PS4 generation beginning to end. None of Sonys 1st party titles were 60fps in single player aside from GT. Only for multiplayer and sport was 60fps common. But resolution wise there was a point where some 3rd party games like Jedi order were delivering 720p with bad FSR upscalling + sub 30 frame rate. It seems like some devs were optimising around the Pro consoles at that point lol. 

If they are to succeed they need to keep consoles as a mass market device. If the price is $699+ consoles risk losing their place in the market. They are a mass market device that offer a low cost and simple entry point to gaming. They don't need to be powerhouses, so prioritising specs over price would be a huge mistake, for a base model at least.

If the rumours that they are prioritising affordability are true (which coming from MLID might not be worth anything) I would be very happy.

We already have diminishing returns, people already complain the gens leap are too small, so a console now needs to seek appeal beyond just more power. Price and a simple streamlined experience are what they need to lean into hard.

Let's have a console that's small again, let's have one that's cheap but balanced and takes full advantage of the latest technologies to deliver a great experience at a low price.

Honestly with modern technologies like much better AI upscaling the Series S+X approach could work better now. If the storage and ram isn't as heavily compromised either.

The base PS6 doesn't need to be a 50TF machine that costs $799 that people are bound to call the smallest generational leap anyway.