iMac 2010 27" (11,3) with hd5750

[BarresB]

hi, i got a free iMac (2010 27" (11,3) with hd5750) for some testing and I wanted it too use it with MainStage, but that needs MacOS 11.4. (i fortunately had a SSD and some extra memory laying around)

So i thought, maybe i can install the patch from DosDude1 to get it to Catalina. After that install this patch for maybe a little support in the graphics section. So I did, and the system isn't working terrible, but it's clear that the graphics aren't what they are suppose to be. Opening applications with the dock/finder is ok I guess, but things like Launchpad are terrible and VLC can't play any video.

Was I to optimistic for trying this? Or is this just a hopeless case?
I was looking for a gtx765m, but those are getting expensive, even though I haven't put any money into this. I feel like that would be too big an expense for an 11 year old iMac.

Could somebody tell me if it is somehow possible without a new card?
I did read this in the notes: Support AMD/ATI Radeon HD 5xxx and 6xxx series