I just released my ‘Bulk MB Image Uploader’ shortcut:

This shortcut helps you to upload sets of images to your Micro.blog account and copy the resulting image URLs (optionally as Markdown) to the clipboard for easy sharing or editing. Get items from the share sheet, or run it without input to choose from sources like Files, Photos, the clipboard, and the camera.

Get it from the HeyDingus Shortcuts Library.