I agree re: Anker.I would recommend the " Anker " brand. They are well made to a high standard. We've been using a 10,000mA version which is compact and versatile. Some of the alphabet spaghetti named brands on Amazon are of questionable provenance and I wouldn't be comfortable charging them.
Agree about Anker as I have one of their wireless chargers and it's performed well over the years I've had it. Phone support too.
If you can't get Anker, try the Juicy brand which sometimes does deals through Lidl/Aldi. This powerbank fell out of my pannier and was run over by a farmer's 4*4 a few years ago. Still works and use it as a spare.