you wouldn’t lose any apps or anything Dany, this has been covered by gelbuilding a few times in other threads and just requires a few changes. if you follow this thread below you will be able to find a lot of information to get you started and if you have any hassle there’s plenty folk around that will give you a hand. the thread covers a few different topics so if you scroll through you can figure out what you want to use https on with good details from gelbuilding.
It depends if you want to expose apps to the internet or just want to use https and have a certificate for the web ui and apps internally. you’re right that it can get somewhat complicated especially when you aren’t sure what you want to use https for and haven’t done it before it can seem daunting. gelbuilding is a good person to speak to on the subject. I was thinking the thread would help inform you in making a plan for what you want to achieve so others can help guide you through the process.