wonder if relate to bwacks https://github.com/bwack/VHDL6526 https://www.youtube.com/watch?v=FLxncR7Ru4Y
8520's can still be gotten NOS from Analogic and probably a few other places but there are also a couple of projects in progress at the moment to replace the CIA's
https://github.com/niklasekstrom/cia-verilog
https://github.com/bwack/VHDL6526 (6526 and 8520 differ only in their TOD clocks so it should be simple for this to support both kinds)
I don't think you will see new custom chips made to match those chips, however they are small enough to be easy to implement in a modern CPLD/FPGA.
I know of three such projects at the moment:
J-CIA: https://1nt3r.net/j-cia/
FBI: https://www.forum64.de/index.php?thread/84273-wip-fbi-als-er...
VHDL6526: https://github.com/bwack/VHDL6526
The 6526 CIA from the C64/128 is almost identical to the 8520 from the Amiga, the only difference is in the time-of-day clock registers. The 6526 uses BCD encoded TOD, the Amiga 8520 counts seconds since midnight.