A Raspberry Pi would work but if you start to host a lot of your own data it will start to struggle. An older computer or laptop would do the job maybe with a Ram and SSD upgrade.
I would go with Start9 over Umbrel as a personal preference. You can buy their Embassy One Raspberry Pi for ~$500 or download the software onto an existing Pi or computer.
Guide:
This is the link I was looking for!
Though, can I build that with this? GeeekPi Raspberry Pi 4 8GB Starter Kit - 64GB Edition, Raspberry Pi 4 Case with PWM Fan, Raspberry Pi 18W 5V 3.6A Power Supply with ON/Off Switch, HDMI Cables for Raspberry Pi 4B (8GB RAM) https://a.co/d/1vyVaqs
Looks like this is missing the SSD and also has some parts you dont need. Here is their DIY hardware guide for a Pi.
Right, but I can add the SSD for 100 bucks, saving 100.
Yeah?
You would need something to put the SSD in and connect it to the Pi. External enclosures are not reccomended - I went down this road before and had a lot of issues. If you look at the DIY hardware list I posted its a different case with the SSD mounted in the case. A speaker is also advisable as there is no screen and the sounds will let you know what's going on when rebooting etc.
