I have 3 suggestions! because that's how I tend to work too

- Scapple (mac/windows only) https://www.literatureandlatte.com/scapple/overview I love how minimal it is, but wish there was a linux/web version. I'll probably make my own some day.

- kinopio (web/mobile) kinopio.club Works well, but has a strong, quirky personality which sometimes gets annoying for me; I prefer the minimalism of scapple.

- draw.io / diagrams.net You can configure it to hide most of the toolbars and then just use it as mind mapping software, this is what I'm trying at the moment.