Pumps can almost not fail to generate an erection. It may be that for sex, the mechanical procedure isn't for you, or pump or constriction rings were uncomfortable. Did you have a proper demo done on yourself? A proper demo by a clinician who knows how to use it doubles the chance of using it satisfactory when you get home. If yours is a SOMAerect model supplied on prescription or purchased via iMEDicare, they will demo it on you. At the moment because of COVID, this is via a videocall. iMEDicare also put together a new video at the beginning of COVID to cover some of what they cover in the in-person demos https://youtu.be/HJWCzzII1oI
Six months after the op is too soon to decide things have failed, because you could well still be recovering.
If you think it's unlikely PDE5 inhibitors will work (Viagra, Cialis, etc) because they require working nerves, in terms of drugs, that leaves the vasodilator drugs, mostly Alprostadil based. The most effective are the injections, but there are a couple of others you could try. Vitaros is a cream you spread on the glans or drip into the urethra (depending which type of dispenser you get), and MUSE is a pellet which is pushed up the urethra and dissolves. These don't work for everyone but are probably worth a try. Vitaros can be prescribed by your GP, but MUSE usually needs an ED clinic appointment to show you how to use it before your GP can prescribe it.
The final option you have is a penile implant, but these don't normally happen until at least 18 months after surgery, because you won't have given enough time to see what recovery you're going to get, and to go through all the other ED drug treatments first. Everyone I've talked with who's had an implant thinks they're fantastic. If you had some ED beforehand, you are likely to end up better off than you started.