The low hanging fruit: scratch your own itch.
Almost every startup I've began was a problem I was experiencing myself. In all cases, there was no solution that fit my exact needs.
Why creating a solution for yourself works best:
Create a list of all the tools and services you use. Do any of them make you say "this sucks"? Explore those first. What's something you've always wished it had?
Read this essay by Paul Graham for more insight: How to get startup ideas
Before I provide my process: For physical products, look at Kickstarter campaigns that have reached their funding goals. That's a good starting point for ideas.
I do something against what most people do. I don't do a lot of research when coming up with the idea. Research comes afterwards. Here is my 2-step process...
1. Build a knowledge network
Begin with any space that interests you and look for any seed of an idea. Before thinking too much, start creating a deck. This gets you in motion. Finish the deck that same day. Pitch that deck to 2-3 smart and relevant people and take detailed notes of their feedback.
Questions to ask yourself:
2. Tweak the deck between pitches and try to pre-sell the solution
Just do it. Try to pre-sell the solution to people you pitch it to. See if they're willing to pay you in advance. If they are, you're definitely on the right track.
My process is a combination of ideation and validation. It's not something most people do, but it works for me.
Scratching your own itch is ideal, but can also be risky since many engineers do that, which results in a lot of similar solutions/products/services. It's not uncommon to find out about someone else solving the same problem after you already started building or even after you launch. Simple googling isn't enough. Execution is most important when it comes to competitive products and it's not often a strength of a first time solo-founder with engineering-only background.
That said, a technical person without an idea should talk to people in their network and be on the lookout for problems people describe in their field. Partnering with a domain expert familiar with a problem is a good option for a technical founder.
Consider finding a co-founder, who is a domain expert with an idea, via sites like FounderDating.com and at least look at profiles suggested to you.
You can find others ideas or create your own. I think you can't create anything unless you are a professional in some field. If don't want to steal others ideas you should to become skilled specialist.
And then ideas will appear. If you have right idea maybe you are interested to make it bigger. If so look through these 44 pitch decks presentation https://pitchdeckia.com/. They can help you even create a good idea.