Cost allocation

Good use case — this is a proportional cost allocation pattern. The key is that the divisor (number of teams per product) must be calculated ignoring the current team filter but respecting any product filter, so that the allocation ratio stays correct.
Here's the measure:
daxAllocated Cost =
VAR CurrentProduct = SELECTEDVALUE(Dimension[Product])
VAR CurrentTeam = SELECTEDVALUE(Dimension[Team])

-- Total cost for the current product (respects product filter, ignores team filter)
VAR TotalProductCost =
CALCULATE(
SUM(PurchaseOrders[Amount]),
REMOVEFILTERS(Dimension[Team])
)

-- Total number of DISTINCT teams for the current product (ignores team filter)
VAR TotalTeams =
CALCULATE(
DISTINCTCOUNT(Dimension[Team]),
REMOVEFILTERS(Dimension[Team])
)

RETURN
IF(
TotalTeams = 0,
BLANK(),
DIVIDE(TotalProductCost, TotalTeams)
)
Put this in a table visual with Product and Team from your dimension table as rows. The measure will automatically divide correctly in every filter context.
How it handles your scenarios:

Filtered on TOTO → both TEAM01 and TEAM02 rows show 2500, grand total 5000 ✓
Filtered on TEAM01 → only TOTO/TEAM01 row shows 2500 (TITI has no TEAM01), grand total 2500 ✓
Filtered on TEAM02 → TOTO/TEAM02 = 2500, TITI/TEAM02 = 5000, grand total 7500 ✓

One note: your dimension table has a row for TOTO;TOTO EDITOR;TEAM01 and TOTO;TOTO READER;TEAM01 — that's two rows for the same Product+Team combination. If you want to count unique teams (not unique software+team combinations), make sure DISTINCTCOUNT(Dimension[Team]) is counting the Team column specifically, which it is in the formula above. TOTO will still count as 2 distinct teams regardless of how many software rows exist.

You can create a measure like

Product Cost = SUMX(
    SUMMARIZE( 'Product', 'Product'[Product], 'Product'[Team] ),
	VAR NumTeams = COUNTROWS(
		CALCULATETABLE(
			VALUES( 'Product'[Team] ),
			REMOVEFILTERS( 'Product'[Team] )
		)
	)
	VAR TotalCost = CALCULATE( SUM( 'Purchase Orders'[Amount] ) )
	VAR Result = DIVIDE( TotalCost, NumTeams )
	RETURN Result
)

Hello Jay20024

a relationship between the two tables would be a many to many, so I avoided that overall

Here are the tables I loaded, based on your sample

fact

dimension

Model (no relationship)

Attached the pbix I generated

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Francesco Bergamaschi

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Jay20024 

Allocated Cost = 
DIVIDE(
SUM(PurchaseOrders[Amount]),
DISTINCTCOUNT(DimProduct[Team]),
0
)

Thankyou, Juan-Power-bi, johnt75, FBergamaschi and Kedar_Pande for your responses.

Hi Jay20024,

We appreciate your inquiry through the Microsoft Fabric Community Forum.

We would like to inquire whether have you got the chance to check the solutions provided by Juan-Power-bi, johnt75, FBergamaschi and Kedar_Pandeto resolve the issue. We hope the information provided helps to clear the query. Should you have any further queries, kindly feel free to contact the Microsoft Fabric community.

Thank you.

Hi Jay20024,

We are following up to see if what we shared solved your issue. If you need more support, please reach out to the Microsoft Fabric community.

Thank you.