I know there's an open-source extension to LATEX specifically for chemical formulae - I think it's called chemfig - here's what I just found on quick lookup:
Overleaf - Chemfig
Also, for simple diagrammatic stuff, if you don't feel you need a chemistry formula specific tool, and general graphics / vector drawing works for you, then bear in mind that ...
If you only want to draw them by hand, as you were on a blackboard you can use any simple paint program, there are several free ones.
Take a look ...
Word and Powerpoint or their free rivals such as LibreOffice or OpenOffice have editors for quite rich formulas. They are very easy, but typographic control in LaTeX style is zero.
Structure diagrams need a drawing program. Office products have something quite clunky but easy to learn. Inkscape is the complex but capable one freebie.
Check this molecule ...
You could use the Adobe Illustrator Draw app. It works on Android devices, and is available in the Google Play store.
To add an image, begin a new project. Tap the Layers icon, tap the + icon to add a new layer. Choose "Image Layer", select an image from your gallery or take a photo, or use select one from your cloud files, etc.
If you tap on the image ...
You could check the image orientation in Windows by right clicking an image file, select Properties, and open the Details tab. Not sure if you're using a Mac but I would suspect there will be something similar.
The Dimensions property will show the horizontal side (on the left) and the vertical side (on the right). So, if the horizontal size is the biggest ...
It is good that you want to have your business... But I am worried that you do not even know the basic software.
I am pretty sure that creative people can do Tshirt design using crayons directly on the silk for silk print, or they can do an amazing digital paint in a ton of programs out there, even free ones https://duckduckgo.com/?q=free+painting+program ...
Probably one option is using blender directly.
Motion capture info
Position and skeleton
Render, green screen or even composite a 3D environment or doing camera tracking
Realtime rendering, Not as powerful as a gaming engine, but pretty interesting.
Open source, so you could tweek some things if you need or can.
For the models you could ...