As a chemist, I can say it is true that nearly all finishes are food safe once
fully cured. Also, there are very likely more toxins or allergy causing compounds in the wood than any finish.
That said, many people want to be able to say it is food safe without doubt. (This does generally ignore allergies). Compliance with a certification like FDA does support the safety and that the manufacture backs it, however, as mentioned above that doesn't include testing for toxicity or how the certification/classification is determined. IMO it's better than nothing. In addition one can:
1) Use an edible finish e.g. shellac (used as food coating among other things), mineral oil, vegetable oil...
2) Look at the Safety Data Sheet(SDS) (formally MSDS) required for all products. This shows what chemicals are actually in the substance rather than what the manufacture claims. If this showonly one or two components that are not toxic it is safer than most things. Sectioins 3 ingredients and 11 toxicity are most important. Caveat a) this requires determining what is toxic, and b) "proprietary" compounds are allowed to be excluded.
3) Does the manufacturer provide easy access its food safe criteria and/or its Safety Data Sheet.
Mahoney's does a pretty good job:
https://mahoneysfinishes.com/food-grade-safety-info/
However IMO, it demonizes VOC's. Our food, wines, coffee's would taste pretty poor without a lot of VOC's. SDS shows the only ingredient listed on MSDS is walnut oil.
Tried and True says “100% safe for food contact surfaces." “Linseed oil and beeswax” on the can. MSDS ingredients: “Modified Linseed Oils” and “trade secret”. Sooooo, how modified? secret? Their website goes further in its claim on other safety/environmental issues.
https://www.triedandtruewoodfinish.com/about/environmental-standards/
Having fun Pushing it too far?? are linseed oil, walnut oil, or tung oil toxic? Warning - google with give many different and wrong answers. See SDS.
Linseed: SDS: Linseed
Following ingestion "Rinse mouth with water. Do not induce vomiting. Never give anything by mouth to an unconscious person. Call a doctor or Poison Control Center immediately." ?? Does not sound good! That's likely for drinking it straight. Section 11 No other toxicity data listed
Walnut Oil: SDS: No acute or cronic toxicity. Ok, its a vegtible oil
Tung Oil: SDS: Section 11 toxicity either says not toxic or no data. But for fun see the SDS for Minwax tung oil especially sections 3 & 11
https://web.mit.edu/tsg/sds/minwax_tung_oil.pdf Finishes labled "pure tung oil" are often not.
Sorry for the long post, you decide.
Lary