When you buy an ARM from ST or Espressif, the license is already paid for. We have no shortage of ARM on the market or every other non-arm chips on the market.

Changing to RISC-V should theoretically lower the price to comparable ARM chips because there is no license to pay, but the buck stops there.

If a company develops a product with a RISC-V chip, they can still create a walled product. The underlying chip architecture does not prevent a company from being a dick.

The Atmel Atmega/AVR is just an old architecture from before ARM became widespread. And Arduino is a project that streamlined code loading onto a chip to make creative art more accessible to non-technical people and caught on. It could have been done on Microchip PIC or the Texas Instrument MSP, both widespread architecture at the time.

What I am trying to say is that we have plenty of hardware to do pretty much anything that we want and the issue of open hardware/firmware is on the companies that create the products and not the chips from the manufacturers.

Edit: Espressif is not ARM based.