External ADC with slow MCU?

Hello,
If i want to use external adc with speed around 10M SPS how fast mcu should be?
Any sugestion for mcu?
Thanks a lot for help

It all depends upon what processing you intend to do with the 10MSPS signal.
For any significant processing, you may need a high-speed DSP microprocessor.

Do you need to just collect and store the data? Or so you need to process the data? Or monitor the data (no storage) and do something in case ADC value is greater than x?
In other words, you may need a very fast processor if you need to transfer a data string each time one is collected.

Also, is it serial or analog data bus from the ADC to micro.

Also, just because then ADC is able to collect 10Mps , do you plan to monitor or collect data that rate?

Data will be processed. I want true rms multimeter.
# i am thinking about wattmeter. So there will be math and mcu should be twice as fast - Two adc chips? I want 10MSPS per sec.
It should be wattmeter for smps. Up to 100khz.
Thanks
* I am really newbie in digitals electronics. I though i can mix some arm processor with adc unit https://cz.mouser.com/datasheet/2/256/MAX1426-1515110.pdf