Trying to recreate a DAX function for Power Query so I can create a table to Unpivot

Hello Everyone, and thank you in advance for your help.

So I have created a bucketing table so that I can attempt to generate a particualar stacked column chart. These are posted below:

Mechanically, this works, but doesn't fulfill the desired outcome. Through a series of measures we count the Disability, CALD, etc. (usertype) data - but due to the fact that the only way we can figure out to generate this table is with the #of sessions buckets as values in a column - the graph that results always looks something like this.

The users *really* want the # of sessions column as the stack value, and the usertype as the X value. As far as I can tell the only way to do this is with the unpivot function, but unfortunately unpivoting isn't as simple as it usually is here.

The session counts we are generating are reactive by a date slider, so we have generated the mith measures. But, if we want to unpiviot the bucket table we need to generate columns in Power Query - at least, as far as we can tell this is the only solution. Other alternatives, if simpler, would be appreciated.

We are working with a base table that looks something like this:

And are using the following expressions to generate the measures we need to count the disability/cald/atsi values by the number of sessions each client has:

First, to count the sessions for each client:

# of Sessions in Client (Measure All) = 

CALCULATE(CALCULATE(COUNT(ClientInSessionByCase[mcs_client])), 
ALLEXCEPT(ClientInSessionByCase, ClientInSessionByCase[mcs_client]))

Then, to bucket the values:

Session Bucket (All) = 
COUNTx(filter(VALUES(ClientInSessionByCase[mcs_client]),
[# of Sessions in Client (Measure All)] >=Min('Session#Buckets'[Start Limit]) && 
[# of Sessions in Client (Measure All)] <=max('Session#Buckets'[End Limit])),
ClientInSessionByCase[mcs_client])

Then, we count for each bucket in the bucket table for the particular usertypes:

Session Bucket (ATSI) = 
CALCULATE(
	[Session Bucket (All)],
	'ClientInSessionByCase'[ATSI Y/N] IN { "1" }
)

Now, I know this is daunting - but we need to somehow either recreate this proccess for power query - or perform a similar proccess as to generate the same values for the bucket table. This will allow us to then unpivot that table, which will allow us to then, hopefully, switch which values end up in the stack of the graph, and which end up as the X values.

Thank you again in advance for the help - and, as stated before: happy to take any other paths that will lead us to the primary objective: switching the x and stack values for the stacked column chart.