Merino wool T-shirts. Cost about 30€ instead of previously used 3€ cotton T-shirts. Can wear one for about 3 weeks without washing, with no body odor. Much more pleasant to the skin, even for doing sports, driving, etc. Also, warm in winter, airy in summer. Plan to switch most clothing to merino wool.
For moisture management/warmth in colder weather, we're also checking out mesh baselayers [1] since merino does not dry quickly under multiple layers.
[0]: https://nuyarn.co.nz/ [1]: https://www.brynjeusa.com/product-category/super-thermo/