ok sir i think as we have single backend dont want to mess with multiple OpenApi files. So when OpenApi 3.2 will came i am not seeing any information about that release. Cant its possible this nested sidebar tags in current openapi version via tags or something just for example i am using this for nested but its just set a header type of things not a expandable cant you implement in a way it will work like what i shared in image before.
here is code i am using currently
in my python fastapi backend

Custom OpenAPI Schema to add tags grouping to the docs page

def custom_openapi():
if app.openapi_schema:
return app.openapi_schema

openapi_schema = get_openapi(
    title=app.title,
    version=app.version,
    description=app.description,
    routes=app.routes,
)

tag_groups = defaultdict(list)

# Go through all paths and methods
for path, methods in openapi_schema.get("paths", {}).items():
    for method, details in methods.items():
        if "tags" in details:
            for tag in details["tags"]:
                if " - " in tag:
                    group, _ = tag.split(" - ", 1)
                    # Keep the FULL tag name so it matches schema
                    if tag not in tag_groups[group]:
                        tag_groups[group].append(tag)
                else:
                    if tag not in tag_groups["General"]:
                        tag_groups["General"].append(tag)

# Convert to Scalar format
openapi_schema["x-tagGroups"] = [
    {"name": group, "tags": tags} for group, tags in tag_groups.items()
]

app.openapi_schema = openapi_schema
return app.openapi_schema

app.openapi = custom_openapi

This looks good! Does this give you what you or do you face any issues?

I'm not sure if I'm in the correct post but I would like this nested grouping to be implemented.
The problem im having is that I have 1 tag called 'API Routes'. Inside this I have multiple tags like products, orders, etc. which is fine. However when there are a lot of sub routes inside products the tag is overloaded with operations. So I was curious if we could add the sub routes by grouping a grouptag

Simple example in openapi.json:

     [
        {
            "name": "product"
        },
        {
            "name": "product_meta"
        },
        {
            "name": "orders"
        },
    ],
    "x-tagGroups": [
        {
            "name": "API Routes",
            "tags": [
                {
                    "displayName": "Product Routes",
                    "tags": ["product", "product_meta"]
                },
                "orders"
            ]
        }
    ]

See the x-tagGroups update. Support nesting tags but also allow just the normal format to be used. What do you guys think?

This looks good! Does this give you what you or do you face any issues?

no its currently showing the top header as a title not a expandable

I'm not sure if I'm in the correct post but I would like this nested grouping to be implemented. The problem im having is that I have 1 tag called 'API Routes'. Inside this I have multiple tags like products, orders, etc. which is fine. However when there are a lot of sub routes inside products the tag is overloaded with operations. So I was curious if we could add the sub routes by grouping a grouptag

Simple example in openapi.json:

     [
        {
            "name": "product"
        },
        {
            "name": "product_meta"
        },
        {
            "name": "orders"
        },
    ],
    "x-tagGroups": [
        {
            "name": "API Routes",
            "tags": [
                {
                    "displayName": "Product Routes",
                    "tags": ["product", "product_meta"]
                },
                "orders"
            ]
        }
    ]

See the x-tagGroups update. Support nesting tags but also allow just the normal format to be used. What do you guys think?

yup i already written currently what i did but unfortunately scalar does not support in ui its just simple ui tweek they will do but they are waiting for open api update idk why