I need an upgrade and the last two Macs I have are PowerBook Pros
The most recent a really, really good 2015 2.8 MHz 16 gig RAM and a 512 SSD I installed. Also Ext SSDs
It is a really really great box.
I'm glad to hear you are still in the land of the living and managing fairly well I gather and your conditions sound rather familiar but I won't dwell on that, considering this old 82-year-old spent too many months in the local hospital last year, that also started with a medical screw up back in 2013.
Anyway back to the subject at hand, why would you think you need to upgrade just because you think your 2015 MacBook Pro is old, especially as it seems to be able to do everything you want to do and more.
Heck, it even has the capacity to run almost the latest macOS if you would even want to or if there was anything you can't do, why bother.
You've already got a nice good working machine without any problems associated with it, or at least you didn't mention any.
"New and improved" is something that Apple flogs that doesn't really exist in actual life.
As EveryMac.com says:
"This model is compatible with the final version of macOS Mojave (10.14), macOS Catalina (10.15), and macOS Big Sur (macOS 11), as well. It additionally supports the final version of macOS Monterey (macOS 12), ..."
With that in hand or available, I would agree with you that you've already got a pretty damn good Mac with that 2015 MacBook Pro.
Maybe I'm just too old-fashioned, but I like my old 2011 27in iMac and I just upgraded from Mavericks 10.9.5, which I really preferred, up to El Capitan 10.11.6 only because the software I was wanting to need was a minimum. Unfortunately, El Capitan remove some of the features I liked and used from their OS applications.
Anyway, just my two bits worth, and welcome back to the ehMac forums and did you get Owen to do the light upstairs and Ellen I hope everything regarding your health continues to improve.
Good grief, my eldest son just dropped in with a surprise visit from White Horse. So must go and visit. Wow what a great neat surprise!!!