I haven't seen LN wallets that really have the features I am looking for.

You see? Will be easier to come with your additional code on an already existing platform/app, instead of building one from scratch.
But yeah, you will need first to use them and see how they work. I hope you already did that with almost all LN wallet apps.

Nowadays, almost all LN wallets (and are plenty) have more or less same functionalities.
So a new one just with a slight different looking is not really necessary.

Look into joining the teams of:

• Zeus LN - one of the best and with a lot of features, and they always need help
• Blixt Wallet - very powerful and complex. Maybe you could help implementing the desktop version for Linux
• Mutiny - small team that need more help too
• Electrum - one of the oldest BTC wallet
• OBW - this one you can even take over the whole code and maintain it /improve if you want. The dev (fiatjaf) some kind of abandoned it, but is a great app that should be continued.
• Nayuta - still in beta but promising
• BoltCard wallet
• Blink

... and many more. See all kind of LN wallets and their functionalities here in the guide I wrote about.