I did such script a long time ago.
I should start by asking, how much disk space do you have for this?
Local images are cheap:
+--------+---------+ | number | size | +--------+---------+ | 22 | 2108819 | +--------+---------+
eswiktionary +--------+--------+ | number | size | +--------+--------+ | 14 | 390539 | +--------+--------+
frwiktionary +--------+--------+ | number | size | +--------+--------+ | 6 | 702706 | +--------+--------+
dewiktionary +--------+---------+ | number | size | +--------+---------+ | 104 | 4943453 | +--------+---------+
enwikiquote +--------+------+ | number | size | +--------+------+ | 0 | NULL | +--------+------+
eswikiquote +--------+------+ | number | size | +--------+------+ | 0 | NULL | +--------+------+
frwikiquote +--------+------+ | number | size | +--------+------+ | 0 | NULL | +--------+------+
dewikiquote +--------+---------+ | number | size | +--------+---------+ | 17 | 2236129 | +--------+---------+
enwikibooks +--------+-----------+ | number | size | +--------+-----------+ | 2716 | 153301990 | +--------+-----------+
eswikibooks +--------+------+ | number | size | +--------+------+ | 0 | NULL | +--------+------+
frwikibooks +--------+---------+ | number | size | +--------+---------+ | 169 | 8244783 | +--------+---------+
dewikibooks +--------+------------+ | number | size | +--------+------------+ | 7697 | 2772943547 | +--------+------------+
but the commons files will start requiring a bit more space (about 1 TB):
enwiktionary +--------+--------------+ | number | size | +--------+--------------+ | 724855 | 154587222013 | +--------+--------------+
eswiktionary +--------+-------------+ | number | size | +--------+-------------+ | 18938 | 12918158214 | +--------+-------------+
frwiktionary +--------+--------------+ | number | size | +--------+--------------+ | 560321 | 146933557784 | +--------+--------------+
dewiktionary +--------+-------------+ | number | size | +--------+-------------+ | 933737 | 84462331479 | +--------+-------------+
enwikiquote +--------+-------------+ | number | size | +--------+-------------+ | 55186 | 98435989071 | +--------+-------------+
eswikiquote +--------+------------+ | number | size | +--------+------------+ | 5712 | 7522618990 | +--------+------------+
frwikiquote +--------+-------------+ | number | size | +--------+-------------+ | 7348 | 11151209748 | +--------+-------------+
dewikiquote +--------+------------+ | number | size | +--------+------------+ | 4211 | 6149070638 | +--------+------------+
enwikibooks +--------+--------------+ | number | size | +--------+--------------+ | 106405 | 133670795995 | +--------+--------------+
eswikibooks +--------+--------------+ | number | size | +--------+--------------+ | 44309 | 122871671629 | +--------+--------------+
frwikibooks +--------+--------------+ | number | size | +--------+--------------+ | 98843 | 248629243582 | +--------+--------------+
dewikibooks +--------+-------------+ | number | size | +--------+-------------+ | 69669 | 54020348470 | +--------+-------------+
All of them: +---------+--------------+ | number | size | +---------+--------------+ | 2021173 | 981218142389 | +---------+--------------+
for wiki in enwiktionary eswiktionary frwiktionary dewiktionary enwikiquote eswikiquote frwikiquote dewikiquote enwikibooks eswikibooks frwikibooks dewikibooks; do echo $wiki; sql "${wiki}_p" "SELECT COUNT(img_name) AS number, SUM(img_size) AS size FROM image;"; echo; done for wiki in enwiktionary eswiktionary frwiktionary dewiktionary enwikiquote eswikiquote frwikiquote dewikiquote enwikibooks eswikibooks frwikibooks dewikibooks; do echo $wiki; sql commonswiki_p "SELECT COUNT(img_name) AS number, SUM(img_size) AS size FROM image WHERE img_name IN (SELECT DISTINCT gil_to FROM globalimagelinks WHERE gil_wiki='$wiki')"; echo; done SELECT COUNT(img_name) AS number, SUM(img_size) AS size FROM image WHERE img_name IN (SELECT DISTINCT gil_to FROM globalimagelinks WHERE gil_wiki IN ('enwiktionary', 'eswiktionary', 'frwiktionary', 'dewiktionary', 'enwikiquote', 'eswikiquote', 'frwikiquote', 'dewikiquote', 'enwikibooks', 'eswikibooks', 'frwikibooks', 'dewikibooks')) ;