I take ferralet. It is a prescription iron supplement and is easy on the gi system. You may want to try that before you get infusions.
I have tried to find gentler options, but I live in Australia and none of the formulations that people recommend are available here. I checked the one you mentioned, Ferralet, and it isn’t available here either, darn it!
I have considered ordering from the US, but the postage is expensive and I can’t really afford it for something that I would need to be taking for a long time or even indefinitely.