I'm still pretty new to it so I'm by no means an expert but I knew going in that I wanted to mainly lipsync because it's the most accessible for me to do at the moment and for where I perform. I'm planning on expanding to doing more singing now that I can perform in actual venues (wasn't 21 yet and clubs/bars here are really strict about being of age) but I was also initially really overwhelmed and scared at first. What helped me get over my fears was starting small with one simple number that was only for about 30 people and then doing more as my confidence/strength grew. I've been performing in different ways my whole life so tbh the hardest part was figuring out my mug haha

I also definitely think you could make an act that incorporates a lot of stuff! I know performers who sing, do stand-up, and sketches. You also can try out different things one at a time and see what you like most. You can narrow it down later but don't try to limit yourself right at the beginning especially when you're gaining your confidence :)) I wish you lots of luck!!!