Custom pages can call power automate instant flows, it’s quite performant too if you’re worried about the user experience. Think of it like a web service call that you are doing and Power Automate is your backend service.
you can pass in parameters from your app as a JSON object or have a parameter for each input, Power automate can then parse the JSON or read each individual input, retrieve the data you need and format it in another JSON response or several outputs. You app then continues with your tasks after reading the outputs.
FetchXML is an option on the Dataverse List Rows action so you can pre-format it and simply plug in your inputs to the XML.
Try it out if you can, I would say it’s more maintainable than a PCF control unless you’re a pro dev that can make updates on the control as you need to.
