Be careful spending time writing software/firmware for chips that may disappear tomorrow. Cost of the chip itself isn't everything, in fact it's one of the least important things if you're looking at long term cost. This is especially relevant in the current chip shortage climate which has made this point quite salient.
Whether it's a hobby project or a high volume production project, you don't want hundreds of hours of your time spent developing for it to go down the drain. In case of a hobby project, it probably means the one or two units you made are all that you're ever going to make. In case of a product you built in high volumes, it means a large gap in sales and lost revenue while you re-do the firmware for a new chip.
This is a real concern. A lot of these offerings are not useful now because they are not ARM (or, soon, RISC-V). Even with instruction set match, moving between vendors is a huge issue.
Whether it's a hobby project or a high volume production project, you don't want hundreds of hours of your time spent developing for it to go down the drain. In case of a hobby project, it probably means the one or two units you made are all that you're ever going to make. In case of a product you built in high volumes, it means a large gap in sales and lost revenue while you re-do the firmware for a new chip.