I know some people like to do Lighthouse checks to see if changes and features improve or worsen the scores.

What do you use for that?

We are starting to talk to some friends and acquaintances to see if there is a fit. No results yet to report.
Let's see 😊

It does, thank you. Yes, we noticed this after the first few projects we built. Validating an idea first, before you build it and collect interested customers, makes a lot of sense to not waste your time. The typical traps.
We mostly left all of our products online, even if we don't focus on them at the moment, and play the long game.

Our main weakness is our failure to keep being consistent with the marketing approaches we take. Doing a little every day. Especially, if there is other stuff going on, including part-time freelance work.
With the lack of consistency we also didn't try all the avenues, never produced videos and did not try enough actual advertisement.

Thank you for the feedback and insights.
I agree with most of it, and I am always interested in improving myself. Representing the brand in person was never an issue, it's the online part of it all.
Learning something new is exciting, even though I rather delve more deeply into tech, not marketing. For now, we still want to see if an addition to our team makes sense, to play into everyone's strengths.
I'll think about the 3 things that we need to grow in and see, if there is more insight there, than my first thought's I had about it.

Thank you for the offer to chat about it. I might take you up on that.

Did you sell the app in the end? Or shut it down?

We (coders.fail) have some Shopify apps. If you stay on it, have a good USP and marketing, it can definitively work. I know some people who did it and are happy. We didn't focus enough on it and are currently working on something else.
I'm always of the opinion to not put your eggs all in one basket, at least when you have some eggs. Starting out and working on some apps that give you some income, seems like a good approach.
If you have some questions, let me know.

This one. Supports more languages and self-hosting.
Works in many environments and has many integrations for desktop apps as well.

We've never had to transfer accounts, but also had our fair share of issues with Chargebee. For a bigger and complicated project (a marketplace with a mix of one-time and subscription payments with a variety of add-ons and German billing systems) they were willing to improve and change some of their APIs.
During the work with their dev team, we noticed multiple bugs in the APIs, pre-existing or freshly introduced ones, failure to notice API changes of third-parties they relied on and failure to deliver on-time and what was discussed.

The end result was APIs that 20 seconds to calculate prices, webhooks that took multiple minutes to arrive, changed behaviour of production APIs without publishing a new version and the shutdown of their Stripe bank transfer integration, since they realised they cannot support it any more.

After this experience, we decided, it would not be wise to be a long-term client of them.
The amount of frustration experienced and time lost because of them, probably doesn't fit in one post :)

We've tried to use free tier services for as long as possible. Like the free tier, betterstack.com for monitoring has been enough for us.
Cloudflare takes care of a load of load and other features, like custom domain caching.
Most of the costs we have come from tools like Google Workspace and Notion, where we pay per seat and cannot really share it.
Things like VPN accounts and 1Password family is shared more easily with friends or partners.

As @robreckham and I are collaborating as #codersfail in our projects and indie hacker journey, we are kind of already sharing all the tools.
The Hetzner VPS we also user for our personal freelancing projects and help each other out with our skills.