Unsolicited advice, but I’d recommend getting a BBAI64 in your hands before figuring it’s a good fit for BBAI replacement. It’s awesome computationally but it is physically larger and puts out quite a bit of heat - we had a tight area to fit the processor board and it wouldn’t work without a mechanical redesign.
I can only wish we had anticipated the parts shortage better in general and specifically for the BBAI. We had a system running with the BBAI and the PRUs and were hoping to use one or more of the C66 DSPs. We dropped back to the BB Black, then I spent weeks battling SPI and I2C device changes and code space issues on the PRUs (BBAI 12k instruction RAM, BBB 8k). I haven’t expended that much effort for 2-3Kbytes of space since the 90s.