Apps Script to deploy a Google Sheets file as a JSON web app.

Code.gs

// Create JSON URL
function doGet(req) {
  var values = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Sheet1').getDataRange().getValues();

  var output = [];

    for (var i = 0; i < values.length; i++) {
    var row = {};
    
    if (i == 0) { // skip the header row
      continue;
    }
    
    for (var j = 0; j < values[0].length; j++) { 
      if (!values[i][j] || values[i][j] === '') { // skip if cell is undefined or empty
        continue;
      }
      row[values[0][j]] = values[i][j]; // use the value from the header row as the property name
    }
    
    // Only add the row to the output if it has data
    if(Object.keys(row).length > 0){
      output.push(row);
    }
  }
  
  return ContentService.createTextOutput(JSON.stringify({ data: output })).setMimeType(ContentService.MimeType.JSON);
}