Humans were cleansing with soapwort back in the stone age, so likely were in ancient Greece too. I suspect most of the oils listed in the OP were not used until relatively recently, have you tried extracting the oil from grapeseeds without modern machinery? If you want to be authentic use oils and butters that can be extracted using traditional 'cottage industry' type methods and contain fatty acids that can 'nourish' the scalp or hair - olive, palm fruit, shea butter and coconut oil for example. Mineral oil and petroleum jelly will just build up, not penetrate.
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond/ fractionated coconut oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Au Naturale styling gelee
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect