The Tandy 1000 FAQ indicated that some were out there somewhere:
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II.J.3. Can I install a Tandy DAC or 3-voice chip in a normal PC?
Probably not. Tandy once made a PSSJ expansion card ("PSSJ" is the name of the sound chip), but they are very rare. If you find the card, you will need to jumper it for IRQ 7, DMA 1, as software for the Tandy DAC expects those settings. The "SayIt" card from Roar Technology of Canada may be the same (see section III.B.7.).
There are emulators for the 3-voice chip if you want to play your old Tandy games on a newer PC. Check out the Tandem emulator, for example.
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It's amazing these exist.. seriously. I remember when we were talking about doing the three channel TI chip ISA card there was a sidebar conversation about this. So many questions... since the same IC did the Parallel, Serial, Sound, and Joystick (PSSJ) did these cards just have configured the sound only? It doesn't look like there are really that many other ports on them.
Edit: I see the joystick header. How about parallel and serial?
Be curious how they kept those from interfering with existing parallel and serial in a system they plopped these into.