We can have such a device from iWorx with the TA 220 for a view thousand dollars:

but the device is not open source and a big machine. Modern components are affordable and small

Key components to replace it are: the AD 8232

the ADS 1115:

And a used spirometer from iworx which can be found on ebay:

Furthermore single board computer like the orange pi 5:

And a community to build it an replace it.