The way they tie in would most likely be brand dependent. I just went thru this with a Glacier Bay Faucet / Drain setup.

They vary: take the old one to a store to get a match. It might help if you know the brand of sink.

Hi, Go to a plumbing store they will probably know the brand and get you what you want.

Good Luck Woodbutcher

Do they normally come with the sink or the faucets?

The sinks are Kohler.

Is there a material I can get that will be resistant to vinegar?

I saw kits that came with the outlet tube, stopper, connection "strap" and the rod that moves the stopper. No they are chrome plates and all that is available from what I know.

Vinegar is an acid. I don't know what one needs to do to clean a WaterPik, but couldn't you do it in another sink without a stopper like this or in a bowl and avoid this problem altogether?

I don’t see any branding on the faucets all

Are the faucets and stoppers always sold as sets?

I don’t see how to remove the stopper.

I browsed through the Home Depot and Lowes websites and don’t see any faucets that look like an exact match

Yes, you can get replacements at lowe's -

https://www.lowes.com/search?searchTerm=replacement+sink+stopper

Here's how to remove the old one -

https://www.homedepot.com/c/ah/how-to-remove-a-sink-stopper/9ba683603be9fa5395fab90112b01e44

Yes, but others said they are not universal. So, I have to get the style that will connect to the rod from my faucet.

I also need the ring that goes around the stopper