I am a total newbie with GPU calculations so please be patient with my questions.

I have Nvidia Quadro P4000. I need to find private key from public key 256bit ecc.
The Kangaroo seems to be unable to cope with this task. I know it can be supported by GPU but here I do not understand how much of GPU is really used by Kangaroo. What I have seen here it uses maximum a few of tens of GPU threads. But gpu has got thousands of them? Also to be sure Kangaroo is bugless is a bit fantasy. Also difficult to debug. Does Nvidia card need monitor to be connected or to have that special dongle virtual monitor from Aliexpress? How is computer creating screen if nvidia is used for calculations?

So I have this idea, please try to understand and estimate if it is feasible? I want to use whole gpu, 1024 threads or more. Each thread would search in a brutal way the private key in very simple manner: instead of multiplying generator point every time with new possible private key I would start every thread on its own ?? -bit space. It would start from initial "private" key and continue with adding generator point, this would be much faster. After adding generator point (+1 gp) gpu will also check X coordinate if it fits already to public key. Easy to debug. So I would have 1024 gpus performing simple task adding generator point and compare just one coordinate, say X. If it would work but one gpu P4000 is not enough maybe GPU cloud rent for 1000euro for 1 month might be enough? At this moment I have no idea how much time would gpu need to perform one iteration step so I welcome any estimations from you.