~20 Realistic T-Shirt Mockups with Smart Objects — Must Work in Photopea (not Photoshop)

Overview I need around 20 realistic t-shirt mockups set up so I can drop my own designs into each one. Each mockup needs a single smart object layer that makes my design look printed onto the shirt — following the fabric's curve, folds, and shadows — not flatly pasted on top. The single most important requirement: everything must open AND edit correctly in Photopea (the free browser-based editor). I do not use Photoshop. Many "Photoshop mockups" break when opened in Photopea, so this is a hard filter for me. What I'll provide The t-shirt mockup images (PNGs I own) — around 20 Sample designs so you can test placement and realism Target design/placeholder size: 4494 × 5097 px (≈15 × 17 in at 300 DPI — a large print area, because my designs are big) What I need per mockup One smart object layer sized to accept a 4494 × 5097 px design, positioned over the print area The print area must cover a significant part of the shirt — large placement, think bachelorette-party tees on Etsy, not a small chest logo Realism built with warping + blend modes + shadow/highlight layers, so the design bends with the fabric and shows through folds and shadows Delivered as layered PSD files that open and edit cleanly in Photopea Technical constraint (please read) Use only techniques that survive the round-trip into Photopea: warping/mesh distortion, blend modes (e.g. Multiply, Hard Light), and shadow/highlight layers. Do NOT use displacement maps or smart filters — these don't carry over reliably into Photopea. Testing — required before delivery You must open each finished file in Photopea, drop one of my sample designs into the smart object, confirm it updates correctly and looks realistic, and send me proof (screenshot or short screen recording from Photopea) for 2–3 mockups before we scale to all 20. To apply Confirm you've built mockups that work in Photopea before (samples welcome) Tell me how you'd handle dark-colored shirts, if any are in the set