Do a pre-offer inspection if you absolutely must waive inspection contingency.

In general, do not waive inspection on a house over 100 years but if they were built in the last 40 years, you can get a pretty good sense of what you’re looking at during a showing. However, the big things you will be missing are the septic / sewer inspection and subtle signs of pests, framing, and drainage issues.
You can bring an inspector or someone who knows what to look for to your showing.
After the showing, try and calculate the worst-case scenario for all the major items that could go wrong and what it would cost to replace everything. Make sure you can afford the worst-case scenario.
I would recommend a moisture meter and a level so you can spot the two biggest issues: water intrusion and foundation problems. Also, bring your phone charger to plug into the outlets. Open and close the doors and windows. Check that the tubs and sink drain easily. Go to the HVAC and water heater and check the age. The production year should be printed on them somewhere.
Homes from the middle of the 1980s onwards will have a lot of things you don’t need to worry about like lead, asbestos, knob and tube wiring, uninsulated walls, and cast iron pipes.
Works Cited:
https://www.investopedia.com/articles/mortgages-real-estate/08/home-inspection.asp