@debby https://xdaforums.com/f/xiaomi-redmi-5a-roms-kernels-recoveries-other.7681/
Plenty of ROMs at this forum. You're unlikely to get any official ROMs so you won't have seamless updates but it's better than nothing. Usually most ROMs don't come with google but allow you to install it as an add-on. So you'd just not do that part.

@Starcross @debby That's the 5A, not the A5. I know, I know...

As others said, this one's quite new: https://xdaforums.com/t/redmi-a5-4g.4750204/

Redmi A5 4G

This is a new phone, released this year, because it's new I couldn't find any custom ROM/GSI, can anyone help me? Or should I just wait? https://www.mi.com/global/product/redmi-a5/

XDA Forums
@debby @jandi noooo Google gave me the wrong thing 😭