SAMSUNG Galaxy Watch 42mm 46mm Gear S2/3/4 Active対応 デニム&レザー 時計バンド 20mm 22mm - Disk House
Galaxy watch 6 has a new quick release style with a single button, and even more overhang under the lugs. Seems to still be the same 20mm width, so should be compatible
Olixar Milanese Samsung Watch 20mm Strap - Black - Mobile Fun Ireland
Samsung Galaxy watch 4 watch band black - 20mm - Watchstraponline.com
Silicone Sport Replacement Watch Band for Samsung Galaxy Watch 5/Watch 5 Pro,20mm Soft Adjustable Strap for Galaxy Watch 4/Galaxy Watch 4 Classic Women Men - Walmart.com