How to choose microcontroller based on its operating frequency?

None of these things strike me as needing 10s of MHz.

O​n chip Flash is very slow, look at parts supporting QSPI, eMMC or SD memory for storage for data logging.

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Newer L series parts have lower power profiles.

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C​ortex-M parts are common, review and understand their capabilities.

I think your best bet is to choose an evaluation board that includes a CAN interface, and hang a BLE module off that.

Then write your program. Use a high-level programming-language (such as "C") and I/O libraries (such as HAL) so you are not tied to a specific processor.

As Tesla DeLorean said, the slowest step is probably writing-to-FLASH, so you might want other non-volatile storage. Often evaluation boards come with EEPROM and/or an SD or micro-SD connector so those are easy options. I'm a fan of Ferroelectric memory (FRAM) which can be written as quickly as RAM but is non-volatile; something like that hung off I2C or SPI might suit depending how much data you have to store.

Then see how fast the processor needs to be to do what you want.

My guess is even the lowly stm32L0 will be quite fast enough if the program makes sufficient use of buffers so the program does not hang while waiting on slow peripherals. Note that you don't need hardware floating-point unless you have many calculations that you need to do quickly (such as FIR filtering or FFT).

But I think right now the key issue is availability. I have seen it suggested that semiconductor shortages will last throughout 2022. Unless this is theoretical, you need to choose a part you can get.

Hope this helps,

Danish

Thanks for the comments. I was making an initial document for the project so I thought I should include some rough calculation to measure the computing requirements before starting anything.