(Thanks to /u/O_MORES for posting this elsewhere)
There’s a brand new HD audio driver for Windows 98/Me called WDMHDA.
Since it’s a WDM driver, it will play nice with the Sound Blaster Emulation Layer built into Windows 98/ME (sbemul.sys).
And it actually works. Here’s Windows 98 and this codec tested on a Ryzen 9 PC: https://youtu.be/uhWyH0TsrCc


This driver will work with any motherboard that’s newer than the 915 chipset (which uses single core Pentiums). So if your motherboard supports dual-core CPUs at the very least, it will be compatible. Ivy Bridge for sure.
I haven’t personally attempted to install 98 or ME on more modern hardware, so I’m unsure if there’s any special steps to do so, or if it just sorta works like it would’ve on an older PC.