>>419632851% seems super small but its actually really not. Just ride up and down the route/enter the next area and come back and it'll reload the "overworld" models. You can cycle around and wait for it to pop up.
Alternatively depending on how far you are, if you have access to the water bike you can go up to Lake of Outrage. Depending on the weather there's a guaranteed Eeveelution up there every day that you can easily capture and breed for eevee.
Speaking of breeding, you can breed that eevee. Gigantimax doesn't pass down.
Or just try surprise trade. I get eevee all the time.