Given your described usage and existing investment in Apple devices, an iPad would perhaps be an ideal device.
If you already own a Mac, you will have the best of both worlds - as both Mac and iPad have their strengths and weaknesses - and together, using Sidecar, are a powerhouse. Neither are a full replacement for the other; some users have preference for Mac, while others find an iPad to be ideal for their needs.
Alone, a modern iPad is a very powerful and portable device; iPadOS has matured considerably in recent years. iPad doesn't run macOS - and neither does it need its potential complexity.
Many users, myself included, now use iPad as their main "go to" device of choice - having foregone the impracticalities of a traditional laptop/desktop computer. On occasion I may need to use a desktop computer for a specific task (usually to perform a firmware update of an obscure USB device unsupported by iPad) - but those occasions are increasingly rare as iPads and iPadOS become even more capable 🙂
In summary, do you need an iPad - or would you benefit from an iPad? With devices that you already have, only you can decide - but given the information that you have provided, an iPad might indeed be an ideal fit!
Be in no doubt, a modern iPad is in no way a dumbed-down device; power-users find all the tools and capabilities that are often needed. By contrast, an iPad provides simplicity where appropriate, removing much of the unnecessary complexity of traditional computers.