Any Sony phone that could eventually end up getting a SFOS port must be added to the Open Devices by Sony.
According to this list the Xperia 10 III is not part of the program yet, this means the chances to see an official Sailfish port any time soon are rather slim.
https://developer.sony.com/develop/open-devices/get-started/supported-devices-and-functionality/
No, it won’t come soon. Leave your hopes and get yourself a X10mk2.
Its a pitty. So for now its goodbye to Jolla and Sealfish for me.
You could try to petition Sony, of course 
Hmmm… not entirely sure that would work.
Still not in the supported devices list, however, these some weeks old additions to sonyxperiadev GitHub could perhaps be interpreted to be a possible sign of something (as in, Sony adding it to the supported Open Devices, no comments or guesses made on any further actions by any other parties) happening sometime soon™. As a previous data point, Xperia 10 II seems to have been added to supported platforms 3 weeks after the initial GitHub repository commit.
And that “sometime soon” it still a 1+ year away…
Yes, indeed, depends on what one counts as “something”. Augmented my original post to describe the reality more clearly.
EDIT: Indeed, I am not quite sure what you mean with your “1+ year away”, since the post you linked shows “SFOS ready” being quite consistently 8-12 months after the “First released” (= 6-10 months after addition to Open Devices Program) for the last 3 Sony devices. But indeed, what “something” is, is up to reader.
Xperia 10 III added to Sony’s Open Devices program: Xperia 10 III added to Sony's Open Devices program - Sony Developer World
fantastic, the prospect of an eventual 6GB memory device to replace the 6GB XA2 Plus i have been using for two and a half years now.
Could mean we get SFOS for the 10III somewhere around April, just after all retailers will have stopped selling them 
Maybe after released 10 III sfos, then Xperia IV came out
I’m not trying to pick on Jolla (I’m sure they would love to support new devices from day 1) but I’m afraid I will, again (as happened with 10II), have to buy a device just to let it sit in a drawer for months.
I know that feeling 
For me, and I guess for the most, a statement by Jolla “We are working on … device”
or other clear statement like this would be the best. Of course without guarantee.
But I’d appreciate it so that I can buy that device for the case mine is broken or when there is black friday, SSV or whatever. And better than having anxiety the device is no longer available.
I experienced all 3 cases already
I can only imagine the outrage if for whatever reason the pre-announced device “without guarantee” doesn’t pan out.
It looks like Jolla started work on a Lena adaptation:
I’m not expecting a port anytime soon, the Android version has moved up to to 11, and it’s the first 5G device, so there’s plenty more to work on.
Xperia 10 II is already running Android 11 so that should not be an unknown entity for Jolla as they say “We recommend updating to Android 11”. I’m more concerned about Jolla’s support for VoNR (Voice over New Radio i.e. 5G).
Well, for me it is just important that they work on the device. If they need 3-6 month, that is okay. Especially because I want to buy a used/refurbished one. It will be easier to get one when some more time goes by.
Wild guess, since this is a 5G device it would be great to introduce Sailfish 5.x supporting 5G (: Timeframe if things work and it takes ~6 months sits nicely for a new release in 2022 Q1-Q2. That would be around 1year after supporting 10II. But as I said that’s all personal whishlist & speculation, being more down to earth I would be happy if the port is actually successful and becomes available at some point
i think the support for the xperia x will be dropped then. the XA2, 10, 10 II and 10 III got update for android 11, see here Sony
I don’t know about porting to the devices, but I think the same Android version for all devices might not make it too difficult. Distinctions would then only be necessary for 64bit or 5G.
So everything is quite simple