I recommend trying Swift/iOS/macOS development. No more editor or framework hopping or megatrees of unmaintained dependencies spewing dependabot hell. You will be using Xcode with Apple's APIs to build exciting things that often weren't possible with web tech alone. SwiftUI is easy to learn if you know React. The skills are in demand. The Swift/iOS communities are mature and supportive. Apple's hardware isn't going to become less interesting or less popular any time soon (Apple VR/AR products are on the horizon). Swift is a very nice language; much more fun to use than JS/TS.
Downsides are ecosystem lock-in, general lack of openness when you run into bugs with Apple's APIs, having Apple as a gatekeeper between you and your customers, and not being able to use latest Swift language features or APIs due to minimum OS versions, but if you're prepared for all of that it's a satisfying ecosystem to work in.
Others here are recommending backend, but having been in a similar position to you I get the feeling you might not love it. Large modern backend services are often just as over-engineered and prone to cargo-culting as frontend. You will likely spend more time writing YAML than you feel you have the emotional energy for. The cloud certificate courses people will send you on will feel like sales and marketing systems designed to lock you into building end-to-end solutions with a provider's stack; not satisfying education that promotes personal growth. You will probably have to be on-call, which is not as common for frontend or mobile/Swift devs. By all means explore it, but I'd be a little more careful on that path.
Good places to start are:
https://exercism.org/tracks/swift to learn Swift.
https://www.hackingwithswift.com/100/swiftui to learn SwiftUI.