You can use the following solution using SUBSTRING and CHARINDEX:
SELECT SUBSTRING(model_interested, CHARINDEX('"model":"', model_interested) + LEN('"model":"'), CHARINDEX('"', model_interested, CHARINDEX('"model":"', model_interested) + LEN('"model":"')) - (CHARINDEX('"model":"', model_interested) + LEN('"model":"')))
FROM table_name
To get the whole property (with property name and value) you can use the following solution:
SELECT SUBSTRING(model_interested, CHARINDEX('"model":"', model_interested), CHARINDEX('"', model_interested, CHARINDEX('"model":"', model_interested) + LEN('"model":"')) - CHARINDEX('"model":"', model_interested) + 1)
FROM table_name
You can also use JSON_VALUE to get the expected value, but you have to change the data to a valid JSON value:
SELECT JSON_VALUE(REPLACE(REPLACE(model_interested, '{[', '[{'), ']}', '}]'), '$[0].model')
FROM table_name
demo on dbfiddle.uk