Yes, they only show to admins and no, these banners convey very important messages so they should not be dismissible.
First, the wizard notice,
- there was an issue with the link not rendering correctly. That issue is now resolved. Please update to the latest and it will go away.
- If you see that banner on your site, then you’ve not finished the site setup wizard. We strongly recommend that you do. Once you complete the wizard steps, the notice will go away.
Second, the bootstrap mode notice
This is linked to the number of users you have on your site. It’s there to let you know that your site is still in bootstrap mode. Once you have 50 users on your site, the banner will go away within 24 hours.
If it bothers you that much, then you can use CSS to hide it.