您可以使用:checked伪类来获取所选的单选输入，然后使用循环来创建按钮（使用document.createElement）并将它们附加到容器元素。

const buttonsContainer = document.querySelector('#buttonsContainer');
document.querySelector('#done').addEventListener('click', function(e) {
  const numButtons = +document.querySelector('input[name=numberButtons]:checked')?.value || 0;
  buttonsContainer.replaceChildren();
  for (let i = 1; i <= numButtons; i++)
    buttonsContainer.append(Object.assign(document.createElement('button'), 
      { textContent : 'Button ' + i }));
});

#buttonsContainer { margin-top: 10px; }

<div id=buttons>
  How many buttons would you like?
  <label>1 <input name=numberButtons type=radio value=1></label>
  <label>2 <input name=numberButtons type=radio value=2></label>
  <label>3 <input name=numberButtons type=radio value=3></label>
  <label>4 <input name=numberButtons type=radio value=4></label>
  <label>5 <input name=numberButtons type=radio value=5></label>
  <label>6 <input name=numberButtons type=radio value=6></label>
  <label>7 <input name=numberButtons type=radio value=7></label>
  <label>8 <input name=numberButtons type=radio value=8></label>
</div>
<button id=done>Done</button>
<div id="buttonsContainer"></div>