2700x 2070super build, new dad looking to confirm a few theories

Hi, new dad here dealing with the brain fog of a newborn so here are some questions (she's doing great and is the most amazing treasure in the world, I'm incredibly happy thanks for asking).

Mobo is Asus x470, 16gb ram, 550w PSU (everything but the GPU is 8-10 years old) .I game at 1440p. No problem with low to medium settings or dlss balanced/performance so not a power user lol. Some demanding games that I play that recently have shown me the limitations of my hardware : TWW3, FF7 rebirth, Space Marine 2 all run "fine-ish" at 45 fps average but parrying during fps drops is getting rough.

Price are in CAD, looking for people to agree/refute/adjust my "theories". Keep in mind this is very budget conscious and mostly to browse deals online and on marketplace.

1: My "Max" upgrade for CPU (on rysen) would be in the 5xxx range according to AI Google, so avoid any 7xxx or higher as I would need to change mobo. 5800x3d is "BiS" but the 500CAD price is a bit too steep for me considering I'm still able to run AAA games fine (on low +dlss). I saw a few 55003xd at 275$CAD used and I'm trying to see if I can negotiate down to 200$ for budget reason. So I'm thinking : look for used "x3d" model in my price range

2: I'm looking into GPUs as well, I'm thinking 3080ti for 500$ or 4070ti for 650$ ? I have an offer at 700$ for a 4070ti but this is a little over budget and I was wondering if it is a good deal or a "wait and see". I'm also looking into the 7800xt-7900xt GPUs which seem to fall into this price range.

3: Should I upgrade PSU no matter what? I keep looking at power calculations with different combos from above and some still seem under 550w but with it being old I feel like I should include a 750W PSU in my budget for most of not all upgrade.

I'm browsing for great deals, not in a hurry. I know value and budgets vary from person to person so here are some numbers to help : ideally I'd stay under 750$ and limit the modifications to my current system. Could do 1000$ for a very good deal on BiS (for like a 5800x3d+9070xt/4070ti combo) or 1750$ for a used computer as I could sell mine for a few peanuts.

Any and all advice/opinions welcome. I fully realize I'm on the lower end with my budget and it might not be the right time to upgrade, so "just wait" could be an option as well.

Thank you for your time !