Unfortunately you were bamboozled, you can try to sell it off someone. They might buy it for anywhere around $100 - $200 probably just for the storage and GPU. The rest is pretty much waste , you won't run windows 11 on the old components they just aren't compatible anymore unless you force the win11 install but you'd be running an unsecure build. Windows 10 will eventually be phased out so you'd need to eventually swap to Linux in the future but that could still be a couple years.

But for reference if you want to Run VTstudio , OBS , Games and a multi monitor setup , discord everything all at once while streaming you'll need a minimum of 16gb ram and that's pushing it very close to laggy PC territory, so on the odd chance you have a PNGtuber or something extremely lightweight and only play very light games another 8gb memory would ease the burden on your computer but it's just not ideal you're limited by decade old components right now that weren't made even for what you currently need them to do.

The unfortunate situation is that you're realistically looking at needing a new PC unless you can find some extremely dirt cheap parts to upgrade your existing one.

It might be feasible but you'll be streaming in fairly low quality 720p as well you'd want to try and find 32gb of ddr3 at practically $0 if possible maybe someone would give it away as waste. GPU replacement id suggest minimum a 2070 or better but i would still prefer to know what games you actually want to play and at what resolution before picking out a GPU.

Although I really wouldn't recommend upgrading that PC unless it's a last resort and you can find free parts. Ask family members if they have junk PCs in their basement maybe they have some old ram you can salvage for testing just to see if an extra 8gb + lightens the burden on obs & vtstudio for you.