If you want to try out the advanced web interface for Mastodon, I made short video on how to pin a hashtag search.
1. In Preferences, Enable advanced web interface and save.
2. Go Back to your Mastodon start page.
3. Search for #FediTips
4. Click search result
5. In the column that appears, open column settings (top right icon)
6. Select โPinโ and the column will stay in your layout and update automatically
7. You can add more hashtags to the same column, if you want.