Selfhosted

If you wanna go nuts on the data, probably Obsidian.md with the built-in Daily Note plugin and the Dataview plugin, which allows you to do all kinds of crazy operations on the data in your vault as if it was a database.

If you wanna go less nuts, obsidian still has tagging, linking notes, daily notes, and all kinds of other stuff built-in and is extensible by things like the Calendar plugin from the community.

And everything is stored as plain Markdown with the occasional hint of JSON (for some plugins) so you're not locked into using Obsidian until the end of time. Your data is yours.

(I realise this sounds like an ad but I've just been using Obsidian for years now and I enjoy it)

Maybe not be exactly what you're looking for, but Logseq has a daily note-taking function. When you open it for the first time of the day, it shows you a blank journal with the current date as the header and you can put whatever you want in it. It has a search function that can search through all the notes you've made for specific text. It saves each day as a separate markdown file and you can sync these to your phone or other devices with Syncthing, a cloud service like Google Drive, or with git if you host something like Forgejo.

The only thing about Logseq is that it doesn't use the standard syntax for Markdown checkboxes. Instead, it has it's own Todo syntax, which is perfectly human readable without Logseq, but loses out of some convenience if you were to migrate to something else.

Why not use Journal from Silverbullet since you already have it https://silverbullet.md/Library/Journal

You can just copy those templates and edit them as you wish, for example I have one for Stand-ups at work

You have and use Silverbullet. Why not use templates and Silverbullet? It’s basically made for exactly that use case.

If it isn't meant for others to see, what's wrong with a .txt file you just add notes to?

I don't think it will have everything you're looking for, but I really like DailyTxT. I do have a couple other note-taking apps & seeing if I want to replace DailyTxT with Obsidian, but I like the web-hosted & straight-forwardness of DailyTxT.

tiddlywiki?

I personally use private github repo as my diary. I don't want to lose my data by accident. I trust github more than I trust myself

Obsidian is great for note taking and creating pathological atomic notes that connect to each other