@SoHotSoup sure it is possible, via custom scripts. In general the suggestion is that if you have 2 app projects in the repo then add it as 2 separate apps on bitrise.io
Skipping steps is definitely possible if you’d prefer that, but requires scripting. Related docs: https://devcenter.bitrise.io/tips-and-tricks/disable-a-step-by-condition/ - for scripting see the last section / the bottom of the page.
A related discussion with a script & run_if example: How can I use variables stored with envman in the run_if check before a step is run?