Welcome back.

Make sure you have the HSV-010 in your garage, it's a great-sounding car that handles well with the G29. Also, try out Toscana too, I've been dying for the one featured in Course Maker to return to the GT franchise with its full Italian time-transitioning and landscaped glory; the Dirt track was good too.
As a GT seven user what should I expect of GT five. I honestly don’t remember what it was like playing at last?
The same feeling, but on inferior physics and graphics. One distinct feeling I had driving high-powered cars was that they felt kinda detached from the road while using a wheel compared to GTS/7, in the sense that they are very easy to go off-track and the wheel does not have enough sensitivity(?) to let you countersteer at just the right amount.
I’m also glad I didn’t sell my old playseat and G29 as that works a treat on GT5 on the PS3.
That's a very fortunate thing that you still kept your Playseat and Logitech G29, because I think it's the only Logitech wheel (or even from any brand, really) that still supports major racing games released in the Playstation console family counting from the PS3 onwards, and yet also handles great. My G29's pedals have their wiring malfunctioning, so I got a Thrustmaster T300 RS as replacement without fixing the G29. The T300 RS is decent on PS5's GT7, although it's still inferior to the G29 on that game to me. But, I don't know if I've said this before on the 'Planet, even though it supports the PS3 as well, the T300 RS does NOT handle anywhere near as good as the G29, at least in GT5, the only PS3 game I've tried both wheels on. You might do okay with an underpowered car, but once you go to try a high-powered car at a twisty circuit (like Super GT cars at the Nordschleife), it handles terribly, because there is hardly any force feedback perceptible in your hands. And IIRC there is no option to adjust the FFB strength in GT5, or at least such an option has no impact on the actual strength delivered on a T300 RS.
There may be another wheel made by a different manufacturer that can do PS3+4+5 games with decent feeling and haptic feedback, but AFAIK, the G29 is the only option (and your safest bet). So keep it if you intend to keep on playing GT5 with a wheel.