How to check a VPS configuration (Nest and React)?

I need to update the web app of a client of mine. That webapp uses nest as a backend (along with Prisma and SQLite) and react as a fronted. Everything seems to run off a VPS running Ubuntu.

I have a couple of questions since i've never used a VPS before :

How do I check the configuration of the VPS so that I can update the front-end and/or the backend without crashing the whole system and losing all the DB data ?
Is it necessarily using nginx ?
Thank you in advance

Hello, your topic has not been answered for 4 days.

I invite you to mention the offer you have and more technical elements so that the community can better understand the situation you are in.

^FabL