So, as you've already discovered, having the suffix is necessary to retrieving data from that (and all other) endpoints. What you could do before making the request to that endpoint is use their search endpoint to find the symbol with the appropriate suffix:
import requests
url = "https://query2.finance.yahoo.com/v1/finance/search"
params = {'q': '005930', 'quotesCount': 1, 'newsCount': 0}
r = requests.get(url, params=params)
data = r.json()
And the data...
{'explains': [], 'count': 1, 'quotes': [{'exchange': 'KSC', 'shortname': 'SamsungElec', 'quoteType': 'EQUITY', 'symbol': '005930.KS', 'index': 'quotes', 'score': 23969.0, 'typeDisp': 'Equity', 'longname': 'Samsung Electronics Co., Ltd.', 'isYahooFinance': True}], 'news': [], 'nav': [], 'lists': [], 'totalTime': 9, 'timeTakenForQuotes': 7, 'timeTakenForNews': 0, 'timeTakenForAlgowatchlist': 1, 'timeTakenForPredefinedScreener': 1, 'timeTakenForCrunchbase': 0, 'timeTakenForNav': 1}
Next, retrieve the symbol and then make your next request:
symbol = data['quotes'][0]['symbol']
url = "https://query2.finance.yahoo.com/v10/finance/quoteSummary/{}".format(symbol)
r = requests.get(url, params={'modules': 'financialData'})
r.json()
{'quoteSummary': {'result': [{'financialData': {'maxAge': 86400, 'currentPrice': {'raw': 51900.0, 'fmt': '51,900.00'}, 'targetHighPrice': {'raw': 84000.0, 'fmt': '84,000.00'}, 'targetLowPrice': {'raw': 41000.0, 'fmt': '41,000.00'}, 'targetMeanPrice': {'raw': 54903.0, 'fmt': '54,903.00'}, 'targetMedianPrice': {'raw': 54000.0, 'fmt': '54,000.00'}, 'recommendationMean': {}, 'recommendationKey': 'none', 'numberOfAnalystOpinions': {'raw': 34, 'fmt': '34', 'longFmt': '34'}, 'totalCash': {'raw': 110830834155520, 'fmt': '110.83T', 'longFmt': '110,830,834,155,520'}, 'totalCashPerShare': {'raw': 16316.242, 'fmt': '16,316.24'}, 'ebitda': {'raw': 57610560602112, 'fmt': '57.61T', 'longFmt': '57,610,560,602,112'}, 'totalDebt': {'raw': 15665191714816, 'fmt': '15.67T', 'longFmt': '15,665,191,714,816'}, 'quickRatio': {'raw': 2.327, 'fmt': '2.33'}, 'currentRatio': {'raw': 2.883, 'fmt': '2.88'}, 'totalRevenue': {'raw': 233340506472448, 'fmt': '233.34T', 'longFmt': '233,340,506,472,448'}, 'debtToEquity': {'raw': 5.88, 'fmt': '5.88'}, 'revenuePerShare': {'raw': 34351.812, 'fmt': '34,351.81'}, 'returnOnAssets': {'raw': 0.049790002, 'fmt': '4.98%'}, 'returnOnEquity': {'raw': 0.08306, 'fmt': '8.31%'}, 'grossProfits': {'raw': 83161332000000, 'fmt': '83.16T', 'longFmt': '83,161,332,000,000'}, 'freeCashflow': {'raw': 13390567178240, 'fmt': '13.39T', 'longFmt': '13,390,567,178,240'}, 'operatingCashflow': {'raw': 51968483524608, 'fmt': '51.97T', 'longFmt': '51,968,483,524,608'}, 'earningsGrowth': {'raw': -0.159, 'fmt': '-15.90%'}, 'revenueGrowth': {'raw': 0.056, 'fmt': '5.60%'}, 'grossMargins': {'raw': 0.36016, 'fmt': '36.02%'}, 'ebitdaMargins': {'raw': 0.24689, 'fmt': '24.69%'}, 'operatingMargins': {'raw': 0.11991999, 'fmt': '11.99%'}, 'profitMargins': {'raw': 0.091230005, 'fmt': '9.12%'}, 'financialCurrency': 'KRW'}}], 'error': None}}