Long post, but I hope it helps someone out since it covers web,mobile, etc. MVP to me means being able to build something quick and iterate upon, so while it could be a throwaway project each time it still makes sense to have a preferred solution for each problem space.

I stick to tech I know best and also languages which offers a vast variety of available SDKs and dependencies to consume so I don't need to waste time re-inventing the wheel. I also try to plan for my requirements up front so I can best prepare. In this case, I am building an application that requires authentication, notifications, private + group chat, location awareness, and an admin sites for the CMS, partner portal, etc.

- For data storage, I use postgres for persistence, and redis for caching and other temp things. I'm not an expert at either of these, but I have used both extensively and have enough experience/interest to work through any issues that may come up.

- I use nodeJS + express to write backend services. Example: My web and mobile clients consume a REST service that interacts internally with a data layer service. Since the code is organized very simply and modular, it makes it easy for me to spin up new services that consume existing services, or makes it easy to extend. I have a real time service that could use the same data layer service if needed.

- I try to use SDKs that can solve my problem cheap + quick. This is where planning up front is also valuable because if you can identify which SDKs are available for the languages you are using, you will save lots of time and pain. For example, I'm using connectycube (free up to 10k users) for video + chat because they have flutter SDKs it takes literally 10 minutes to set up and be most of the way there. I use firebase for authentication (its free) on the clients, and for my REST service token verification. Firebase can also handle push notifications, so keep that in mind! I use mapbox for geocoding because it is cheaper than google maps.

- For infrastructure, I was using AWS but switched to DO managed postgres and droplets. I'm still using S3 and cloudfront.

The reason I did this is because I don't have much infrastructure experience and made a few misconfiguration mistakes on AWS that bit me. DO makes it dead simple for now so I can focus on just building my product and maybe some day I will be lucky enough to work with a team who knows AWS :)

- For web, I have the website (hosted using carrd, dead simple website builder. They have a cheap paid plan that lets me do things like add a contact us widget and add a google analytics), while the CMS and partner sites are being built using create-react-app. There is no consumer web app (mobile app only), so really those users will just see the site and go download the apps. Partners can access the partner portal to do things like adding their business listing and any promotions, etc.

- Mobile apps are built using flutter. I've dabbled with swift/swiftUI, kotlin, react-native, and flutter and today I prefer flutter for complex projects that I need on both iOS and android. Regardless of what path you choose, some tips I can offer when you're in the middle ground between a "this is more complicated than what's in the /examples folder" and "any top app that you use on a regular basis":
• Spend a weekend going through the platform specific design guidelines. Open up your favorite top apps on iOS and android and use the same features on both. Notice the subtle differences.
• Read the app store guidelines for both so you know what to expect.
• Plan your application structure. What are the shared states, and how will you share data? Do you need to persist data on the device? What device permissions do you need to manage? What are the top level views? Do you need to make network calls? I used to never do this because I figured hey, its just a toy project!! But, as soon as that toy project turns into a passion pit, I need to make that new features can be added very fast instead of requiring a re-write. Just note the different moving pieces, and organize your code in a way that makes sense.
• Nothing is perfect - flutter web is kinda meh and honestly I think its best anyway to just have separate mobile code, and web code.

Learned a ton over the pandemic, hoping to put all of this to good use and keep learning. All the best!