Generally the advice I was always given is you should have 5-10k at least after closing for things like this. I’ve always kept a lot more than that in reserves due to Jumbo loan requirements in a hcol market.
Idk if the advice has changed over the years, but consider anything critical (water heater, electric panel, roof leak, etc.) can be resolved with 5-10k.
In my market seller typically provides the inspection anyways so you know what you’re getting into. If you’re in a market where seller doesn’t provide inspection and you’re waiving that contingency you should do your due diligence and get an inspection for information purposes anyways so you know what needs to be fixed immediately or should be fixed within X amount of time and plan your finances accordingly.
This is not just on the purchase either. All houses age and even new construction can have issues. Imo long term you should have 5-10k+ set aside as reserves anyways. What if you’ve been living in your house for 15-30 years and the water heater or HVAC goes out?