For indoor use we use pure linseed oil. Linseed oil penetrates the wood, oxidates and hardens in the wood to a natural protection, and layers can be applied like 10 years later without sanding.
For outside, a natural pine tar can be added for extra mould protection
These are all natural and were very popular in the old villages of Canada and Northern Europe
https://www.dictum.com/en/
https://www.dictum.com/en/
For Vedic colours to the above mentioned linseed oil pigment paste can be added, and its ready to be used as paint that never has to be sanded. The whole thing breathes still (chemical paint does not breathe on wood).
After years and years just add new linseed oil paint.
all 100% natural