If you mean the most austere Jain path—maximum non-attachment, strict nonviolence, heavy fasting, and full renunciation—then you should look mainly at monastic texts and ascetic manuals, not just general devotional literature. The core scriptures and works often associated with this spirit are the Ācārāṅga Sūtra, Uttarādhyayana Sūtra, and Daśavaikālika Sūtra in Śvetāmbara tradition, and in Digambara tradition especially Kundakunda’s works such as Samayasāra, Pravacanasāra, and Niyamasāra, along with conduct texts like Mūlācāra and Bhagavatī Ārādhanā. These texts center on restraint, renunciation, inward purity, and austerity. ( jainpedia.org)

If your interest is specifically “not stepping on bugs” and very strict nonviolence, Jain sources describe ahiṃsā for ascetics as extending to the greatest care toward even insects and microbes, not just larger animals. ( britannica.com)

On the question of whether any temples still do this: the strict practices you mention are generally not temple practices. They are practices of Jain monks and nuns, who still live an austere wandering or semi-wandering life in the present day, especially in Digambara communities. Temples are places of worship and support for lay devotion; the severe ascetic discipline belongs to the mendicant order, not the temple itself. ( jainpedia.org)

So, in practical terms:

• Read Ācārāṅga Sūtra for early ascetic ideal and discipline.
• Read Uttarādhyayana Sūtra and Daśavaikālika Sūtra for monastic conduct and restraint.
• Read Kundakunda if you want the most inward, renunciate Digambara style.
• Read Mūlācāra and Bhagavatī Ārādhanā for detailed ascetic discipline. ( jainpedia.org)

If you want, I can give you a short “starter reading order” for the most severe Jain path.