I used a 5 year old i7 windows laptop(was $500 new and I swapped in an SSD for another $80), and use Fusion 360 (can be had for free personal use)...
I dont think any stylus (barring something like a Wacom tablet or purpose built drafting device) nor touch screen is an accurate enough input device to be of real use in 3d modeling without struggle. A mouse works great.
I've made everything from taillight housings for my Triumph to the filtration system in my Fluval 13.5, to brackets to fit the old Fluval light to my QT... spoons to measure coral food.. you name it...
Windows 3d builder app has been great too... I made funnels that fit my chemical bottles with that and some other things...
I bought my 3d printer (Voxelab Aquila) so I could print my own filter system (to get rid of that sponge...) and immedaitly went with Fusion...
I'd forget about an iPad or Fire... I mean.. you can... but why suffer?
(those devices are primarily made to "consume" IP ... not necessarily to "create" it... )