For anyone looking for one, Aim Surplus has Gen5 Glock 19 RSA's in stock currently... I snagged one for the parts box. They don't have a lot of other Gen5 parts, but they do have some OEM and also their "house" brand Gen 3/4 parts in stock as well.
https://aimsurplus.com/glock-oem-rec...bly-gen-5-g19/
No affiliation... but have had no problems with Aim in the past. My order is currently being held hostage in USPS hell somewhere in OH... but I don't think that is their fault.
Having a small stock of common parts is a good idea, and Glock parts have, in the past, been cheap and accessible. Hopefully this isn't a long term change to Glocks OEM parts availability.