In a PostgreSQL crosstab, can I automate the tuple part? - postgresql

Question

I'm trying to do get a tall table (with just 3 columns indicating variable, timestamp and value) into a wide format where timestamp is the index, the columns are the variable names, and the values are the values of the new table.
In python/pandas this would be something along the lines of
import pandas as pd
df = pd.read_csv("./mydata.csv") # assume timestamp, varname & value columns
df.pivot(index="timestamp", columns="varname", values="value")
for PostgreSQL there exists crosstab, so far I have:
SELECT * FROM crosstab(
$$
SELECT
"timestamp",
"varname",
"value"
FROM mydata
ORDER BY "timestamp" ASC, "varname" ASC
$$
) AS ct(
"timestamp" timestamp,
"varname1" numeric,
...
"varnameN" numeric
);
The problem is that I can potentially have dozens to hundreds of variable names. The types are always numeric, number of variable names is not stable (we could need more variables or realize that others are not necessary).
Is there a way to automate the "ct" part so that some other query (e.g. select distinct "varname" from mydata) produces it instead of me having to type in every single variable name present?
PS: PSQL version is 12.9 at home, 14.0 in production. Number of rows in the original table is around 2 million, however I'm going to filter by timestamp and varname, so potentially only a few hundreds of thousands rows. After filtering I got ~50 unique varnames, but that will increase in a few weeks.