params.py

data=['http://google.com?param1=value1',
'https://hello.com?param2=1&param3=3',
'https://hello.com?param1=1&param2=2&param4=4']

final_params=[]
all_prms=[]
for line in data:
	all_prms.append(line.split('?')[1:][0].split('&'))

for line in all_prms:
	for l in line:
		final_params.append(l.split('=')[0])

unique_final=list(dict.fromkeys(final_params))

print(unique_final)

# Shorter one
from urllib.parse import parse_qs, urlparse                                                                            
                                                                                                                      
data=['http://google.com?param1=value1',                                                                               
'https://hello.com?param2=1&param3=3',                                                                                 
'https://hello.com?param1=1&param2=2&param4=4']                                                                        
                                                                                                                      
print({param for url in data for param in parse_qs(urlparse(url).query)}

Amazing !!
Thanks alot