I've tried Silego/DialogSemi/now Renesas GreenPaks and like them a lot.
IMHO awesome idea for programmable "digital dust" at $0.5/chip, which can do many things, including voltage level conversion (1.8V-5V),
I2C,SPI, analog functions, some even have MOSFET SWITCH or whole friggin MOSFET BRIDGE!
Most importantly, its killer feature is reprogrammability on the fly. Chip is so simple that one can know what the each configure bit is for
and flip it over I2C or SPI interface.
But now they have new thing: GreenPAK on steroids - ForgeFPGA.
Which is similarly small package, but has 1kLUT FPGA fabric, some SRAM blocks, IIRC FLASH block etc etc.
At the same price: $0.5/chip.
https://www.renesas.com/us/en/products/programmable-mixed-signal-asic-ip-products/forgefpga-low-density-fpgasFor some reason, whole "series" consists of just one model and Renesas seems coy about promoting it.
It has been some time after the announcement and one still has to jump through hoops if s/he want to play with it..