Short answer YES!!!

Spreadsheets are stored in model ir.attachment

Data sits in the binary field called datas.

If you download the binary file you will see that its just test in json format like below:

{
	"version": 5,
	"sheets": [{
		"id": "a396ebcb-f98f-4fb9-8b70-25590191a586",
		"name": "Sheet1",
		"colNumber": 26,
		"rowNumber": 100,
		"rows": {},
		"cols": {},
		"merges": [],
		"cells": {
			"A1": {
				"content": "sdfsdf"
			},
			"A2": {
				"content": "dfsf"
			},
			"A3": {
				"content": "sdfs"
			},
			"A4": {
				"content": "sfsfs"
			}
		},
		"conditionalFormats": [],
		"figures": []
	}, {
		"id": "488f782f-eac3-48a0-98b9-a2d55bf08acd",
		"name": "Sheet2",
		"colNumber": 26,
		"rowNumber": 100,
		"rows": {},
		"cols": {},
		"merges": [],
		"cells": {
			"C2": {
				"content": "sff"
			}
		},
		"conditionalFormats": [],
		"figures": []
	}],
	"activeSheet": "488f782f-eac3-48a0-98b9-a2d55bf08acd",
	"entities": {},
	"styles": {
		"0": {
			"fillColor": "white",
			"textColor": "black",
			"fontSize": 11
		}
	},
	"borders": {},
	"pivots": {},
	"globalFilters": []
}

From python you can get to the datas field and read/manipulate the data on the spreadsheet.